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2008-02-05writeback: speed up writeback of big dirty filesFengguang Wu1-0/+1
After making dirty a 100M file, the normal behavior is to start the writeback for all data after 30s delays. But sometimes the following happens instead: - after 30s: ~4M - after 5s: ~4M - after 5s: all remaining 92M Some analyze shows that the internal io dispatch queues goes like this: s_io s_more_io ------------------------- 1) 100M,1K 0 2) 1K 96M 3) 0 96M 1) initial state with a 100M file and a 1K file 2) 4M written, nr_to_write <= 0, so write more 3) 1K written, nr_to_write > 0, no more writes(BUG) nr_to_write > 0 in (3) fools the upper layer to think that data have all been written out. The big dirty file is actually still sitting in s_more_io. We cannot simply splice s_more_io back to s_io as soon as s_io becomes empty, and let the loop in generic_sync_sb_inodes() continue: this may starve newly expired inodes in s_dirty. It is also not an option to draw inodes from both s_more_io and s_dirty, an let the loop go on: this might lead to live locks, and might also starve other superblocks in sync time(well kupdate may still starve some superblocks, that's another bug). We have to return when a full scan of s_io completes. So nr_to_write > 0 does not necessarily mean that "all data are written". This patch introduces a flag writeback_control.more_io to indicate that more io should be done. With it the big dirty file no longer has to wait for the next kupdate invokation 5s later. In sync_sb_inodes() we only set more_io on super_blocks we actually visited. This avoids the interaction between two pdflush deamons. Also in __sync_single_inode() we don't blindly keep requeuing the io if the filesystem cannot progress. Failing to do so may lead to 100% iowait. Tested-by: Mike Snitzer <snitzer@gmail.com> Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn> Cc: Michael Rubin <mrubin@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05mm: fix PageUptodate data raceNick Piggin2-7/+39
After running SetPageUptodate, preceeding stores to the page contents to actually bring it uptodate may not be ordered with the store to set the page uptodate. Therefore, another CPU which checks PageUptodate is true, then reads the page contents can get stale data. Fix this by having an smp_wmb before SetPageUptodate, and smp_rmb after PageUptodate. Many places that test PageUptodate, do so with the page locked, and this would be enough to ensure memory ordering in those places if SetPageUptodate were only called while the page is locked. Unfortunately that is not always the case for some filesystems, but it could be an idea for the future. Also bring the handling of anonymous page uptodateness in line with that of file backed page management, by marking anon pages as uptodate when they _are_ uptodate, rather than when our implementation requires that they be marked as such. Doing allows us to get rid of the smp_wmb's in the page copying functions, which were especially added for anonymous pages for an analogous memory ordering problem. Both file and anonymous pages are handled with the same barriers. FAQ: Q. Why not do this in flush_dcache_page? A. Firstly, flush_dcache_page handles only one side (the smb side) of the ordering protocol; we'd still need smp_rmb somewhere. Secondly, hiding away memory barriers in a completely unrelated function is nasty; at least in the PageUptodate macros, they are located together with (half) the operations involved in the ordering. Thirdly, the smp_wmb is only required when first bringing the page uptodate, wheras flush_dcache_page should be called each time it is written to through the kernel mapping. It is logically the wrong place to put it. Q. Why does this increase my text size / reduce my performance / etc. A. Because it is adding the necessary instructions to eliminate the data-race. Q. Can it be improved? A. Yes, eg. if you were to create a rule that all SetPageUptodate operations run under the page lock, we could avoid the smp_rmb places where PageUptodate is queried under the page lock. Requires audit of all filesystems and at least some would need reworking. That's great you're interested, I'm eagerly awaiting your patches. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05mm/page-writeback: highmem_is_dirtyable optionBron Gondwana1-0/+1
Add vm.highmem_is_dirtyable toggle A 32 bit machine with HIGHMEM64 enabled running DCC has an MMAPed file of approximately 2Gb size which contains a hash format that is written randomly by the dbclean process. On 2.6.16 this process took a few minutes. With lowmem only accounting of dirty ratios, this takes about 12 hours of 100% disk IO, all random writes. Include a toggle in /proc/sys/vm/highmem_is_dirtyable which can be set to 1 to add the highmem back to the total available memory count. [akpm@linux-foundation.org: Fix the CONFIG_DETECT_SOFTLOCKUP=y build] Signed-off-by: Bron Gondwana <brong@fastmail.fm> Cc: Ethan Solomita <solo@google.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: WU Fengguang <wfg@mail.ustc.edu.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05Page allocator: get rid of the list of cold pagesChristoph Lameter1-1/+1
We have repeatedly discussed if the cold pages still have a point. There is one way to join the two lists: Use a single list and put the cold pages at the end and the hot pages at the beginning. That way a single list can serve for both types of allocations. The discussion of the RFC for this and Mel's measurements indicate that there may not be too much of a point left to having separate lists for hot and cold pages (see http://marc.info/?t=119492914200001&r=1&w=2). Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Martin Bligh <mbligh@mbligh.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05add mm argument to pte/pmd/pud/pgd_freeBenjamin Herrenschmidt32-121/+121
(with Martin Schwidefsky <schwidefsky@de.ibm.com>) The pgd/pud/pmd/pte page table allocation functions get a mm_struct pointer as first argument. The free functions do not get the mm_struct argument. This is 1) asymmetrical and 2) to do mm related page table allocations the mm argument is needed on the free function as well. [kamalesh@linux.vnet.ibm.com: i386 fix] [akpm@linux-foundation.org: coding-syle fixes] Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: <linux-arch@vger.kernel.org> Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05Page allocator: clean up pcp draining functionsChristoph Lameter2-1/+2
- Add comments explaing how drain_pages() works. - Eliminate useless functions - Rename drain_all_local_pages to drain_all_pages(). It does drain all pages not only those of the local processor. - Eliminate useless interrupt off / on sequences. drain_pages() disables interrupts on its own. The execution thread is pinned to processor by the caller. So there is no need to disable interrupts. - Put drain_all_pages() declaration in gfp.h and remove the declarations from suspend.h and from mm/memory_hotplug.c - Make software suspend call drain_all_pages(). The draining of processor local pages is may not the right approach if software suspend wants to support SMP. If they call drain_all_pages then we can make drain_pages() static. [akpm@linux-foundation.org: fix build] Signed-off-by: Christoph Lameter <clameter@sgi.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Daniel Walker <dwalker@mvista.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05maps4: move clear_refs code to task_mmu.cMatt Mackall1-1/+2
This puts all the clear_refs code where it belongs and probably lets things compile on MMU-less systems as well. Signed-off-by: Matt Mackall <mpm@selenic.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: David Rientjes <rientjes@google.com> Cc: Dave Hansen <haveblue@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05maps4: introduce a generic page walkerMatt Mackall1-0/+22
Introduce a general page table walker Signed-off-by: Matt Mackall <mpm@selenic.com> Cc: Dave Hansen <haveblue@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05maps4: move is_swap_pteMatt Mackall1-0/+6
Move is_swap_pte helper function to swapops.h for use by pagemap code Signed-off-by: Matt Mackall <mpm@selenic.com> Cc: Dave Hansen <haveblue@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05maps4: rework TASK_SIZE macrosDave Hansen6-4/+14
The following replaces the earlier patches sent. It should address David Rientjes's comments, and has been compile tested on all the architectures that it touches, save for parisc. For the /proc/<pid>/pagemap code[1], we need to able to query how much virtual address space a particular task has. The trick is that we do it through /proc and can't use TASK_SIZE since it references "current" on some arches. The process opening the /proc file might be a 32-bit process opening a 64-bit process's pagemap file. x86_64 already has a TASK_SIZE_OF() macro: #define TASK_SIZE_OF(child) ((test_tsk_thread_flag(child, TIF_IA32)) ? IA32_PAGE_OFFSET : TASK_SIZE64) I'd like to have that for other architectures. So, add it for all the architectures that actually use "current" in their TASK_SIZE. For the others, just add a quick #define in sched.h to use plain old TASK_SIZE. 1. http://www.linuxworld.com/news/2007/042407-kernel.html - MIPS portion from Ralf Baechle <ralf@linux-mips.org> [akpm@linux-foundation.org: fix mips build] Signed-off-by: Dave Hansen <haveblue@us.ibm.com> Signed-off-by: Ralf Baechle <ralf@linux-mips.org> Signed-off-by: Matt Mackall <mpm@selenic.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Dave Hansen <haveblue@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05tmpfs: move swap swizzling into shmemHugh Dickins1-11/+4
move_to_swap_cache and move_from_swap_cache functions (which swizzle a page between tmpfs page cache and swap cache, to avoid page copying) are only used by shmem.c; and our subsequent fix for unionfs needs different treatments in the two instances of move_from_swap_cache. Move them from swap_state.c into their callsites shmem_writepage, shmem_unuse_inode and shmem_getpage, making add_to_swap_cache externally visible. shmem.c likes to say set_page_dirty where swap_state.c liked to say SetPageDirty: respect that diversity, which __set_page_dirty_no_writeback makes moot (and implies we should lose that "shift page from clean_pages to dirty_pages list" comment: it's on neither). Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05swapin needs gfp_mask for loop on tmpfsHugh Dickins1-3/+3
Building in a filesystem on a loop device on a tmpfs file can hang when swapping, the loop thread caught in that infamous throttle_vm_writeout. In theory this is a long standing problem, which I've either never seen in practice, or long ago suppressed the recollection, after discounting my load and my tmpfs size as unrealistically high. But now, with the new aops, it has become easy to hang on one machine. Loop used to grab_cache_page before the old prepare_write to tmpfs, which seems to have been enough to free up some memory for any swapin needed; but the new write_begin lets tmpfs find or allocate the page (much nicer, since grab_cache_page missed tmpfs pages in swapcache). When allocating a fresh page, tmpfs respects loop's mapping_gfp_mask, which has __GFP_IO|__GFP_FS stripped off, and throttle_vm_writeout is designed to break out when __GFP_IO or GFP_FS is unset; but when tmfps swaps in, read_swap_cache_async allocates with GFP_HIGHUSER_MOVABLE regardless of the mapping_gfp_mask - hence the hang. So, pass gfp_mask down the line from shmem_getpage to shmem_swapin to swapin_readahead to read_swap_cache_async to add_to_swap_cache. Signed-off-by: Hugh Dickins <hugh@veritas.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05swapin_readahead: move and rearrange argsHugh Dickins1-12/+7
swapin_readahead has never sat well in mm/memory.c: move it to mm/swap_state.c beside its kindred read_swap_cache_async. Why were its args in a different order? rearrange them. And since it was always followed by a read_swap_cache_async of the target page, fold that in and return struct page*. Then CONFIG_SWAP=n no longer needs valid_swaphandles and read_swap_cache_async stubs. Signed-off-by: Hugh Dickins <hugh@veritas.com> Acked-by: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05VM: allow get_page_unless_zero on compound pagesChristoph Lameter1-1/+1
Both slab defrag and the large blocksize patches need to ability to take refcounts on compound pages. May be useful in other places as well. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05is_vmalloc_addr(): Check if an address is within the vmalloc boundariesChristoph Lameter1-0/+8
Checking if an address is a vmalloc address is done in a couple of places. Define a common version in mm.h and replace the other checks. Again the include structures suck. The definition of VMALLOC_START and VMALLOC_END is not available in vmalloc.h since highmem.c cannot be included there. Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05i386: Resolve dependency of asm-i386/pgtable.h on highmem.hChristoph Lameter2-6/+8
pgtable.h does not include highmem.h but uses various constants from highmem.h. We cannot include highmem.h because highmem.h will in turn include many other include files that also depend on pgtable.h So move the definitions from highmem.h into pgtable.h. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05vmalloc: add const to void* parametersChristoph Lameter2-5/+5
Make vmalloc functions work the same way as kfree() and friends that take a const void * argument. [akpm@linux-foundation.org: fix consts, coding-style] Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05Move vmalloc_to_page() to mm/vmalloc.Christoph Lameter1-2/+4
We already have page table manipulation for vmalloc in vmalloc.c. Move the vmalloc_to_page() function there as well. Move the definitions for vmalloc related functions in mm.h to a newly created section. A better place would be vmalloc.h but mm.h is basic and may depend on these functions. An alternative would be to include vmalloc.h in mm.h (like done for vmstat.h). Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05Pagecache zeroing: zero_user_segment, zero_user_segments and zero_userChristoph Lameter1-18/+30
Simplify page cache zeroing of segments of pages through 3 functions zero_user_segments(page, start1, end1, start2, end2) Zeros two segments of the page. It takes the position where to start and end the zeroing which avoids length calculations and makes code clearer. zero_user_segment(page, start, end) Same for a single segment. zero_user(page, start, length) Length variant for the case where we know the length. We remove the zero_user_page macro. Issues: 1. Its a macro. Inline functions are preferable. 2. The KM_USER0 macro is only defined for HIGHMEM. Having to treat this special case everywhere makes the code needlessly complex. The parameter for zeroing is always KM_USER0 except in one single case that we open code. Avoiding KM_USER0 makes a lot of code not having to be dealing with the special casing for HIGHMEM anymore. Dealing with kmap is only necessary for HIGHMEM configurations. In those configurations we use KM_USER0 like we do for a series of other functions defined in highmem.h. Since KM_USER0 is depends on HIGHMEM the existing zero_user_page function could not be a macro. zero_user_* functions introduced here can be be inline because that constant is not used when these functions are called. Also extract the flushing of the caches to be outside of the kmap. [akpm@linux-foundation.org: fix nfs and ntfs build] [akpm@linux-foundation.org: fix ntfs build some more] Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Steven French <sfrench@us.ibm.com> Cc: Michael Halcrow <mhalcrow@us.ibm.com> Cc: <linux-ext4@vger.kernel.org> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: "J. Bruce Fields" <bfields@fieldses.org> Cc: Anton Altaparmakov <aia21@cantab.net> Cc: Mark Fasheh <mark.fasheh@oracle.com> Cc: David Chinner <dgc@sgi.com> Cc: Michael Halcrow <mhalcrow@us.ibm.com> Cc: Steven French <sfrench@us.ibm.com> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05gpiolib: avr32 at32ap platform supportDavid Brownell3-13/+27
Teach AVR32 to use the "GPIO Library" when exposing its GPIOs, so that signals on external chips (like GPIO expanders) can easily be used. This mostly reorganizes some existing logic, with two minor changes in behavior: - The PSR registers are used instead of the previous "gpio_mask" values, matching AT91 behavior and removing some duplication between that role and that of "pinmux_mask". - NR_IRQs grew to acommodate a bank of external GPIOs. Eventually this number should probably become a board-specific config option. There's a debugfs dump of status for the built-in GPIOs, showing which pins have deglitching, pullups, or open drain drive enabled, as well as the ID string used when requesting each IRQ. Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Acked-by: Haavard Skinnemoen <hskinnemoen@atmel.com> Cc: Jean Delvare <khali@linux-fr.org> Cc: Eric Miao <eric.miao@marvell.com> Cc: Sam Ravnborg <sam@ravnborg.org> Cc: Philipp Zabel <philipp.zabel@gmail.com> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Ben Gardner <bgardner@wabtec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05gpiolib: pca9539 i2c gpio expander supporteric miao1-0/+18
This adds a new-style I2C driver with basic support for the sixteen bit PCA9539 GPIO expanders. These chips have multiple registers, push-pull output drivers, and (not supported in this patch) pin change interrupts. Board-specific code must provide "pca9539_platform_data" with each chip's "i2c_board_info". That provides the GPIO numbers to be used by that chip, and callbacks for board-specific setup/teardown logic. Derived from drivers/i2c/chips/pca9539.c (which has no current known users). This is faster and simpler; it uses 16-bit register access, and cache the OUTPUT and DIRECTION registers for fast access Signed-off-by: eric miao <eric.miao@marvell.com> Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Acked-by: Jean Delvare <khali@linux-fr.org> Cc: Sam Ravnborg <sam@ravnborg.org> Cc: Haavard Skinnemoen <hskinnemoen@atmel.com> Cc: Philipp Zabel <philipp.zabel@gmail.com> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Ben Gardner <bgardner@wabtec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05mcp23s08 spi gpio expander supportDavid Brownell1-0/+24
Basic driver for 8-bit SPI based MCP23S08 GPIO expander, without support for IRQs or the shared chipselect mechanism. Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Cc: Jean Delvare <khali@linux-fr.org> Cc: Eric Miao <eric.miao@marvell.com> Cc: Sam Ravnborg <sam@ravnborg.org> Cc: Haavard Skinnemoen <hskinnemoen@atmel.com> Cc: Philipp Zabel <philipp.zabel@gmail.com> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Ben Gardner <bgardner@wabtec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05gpiolib: pcf857x i2c gpio expander supportDavid Brownell1-0/+45
This is a new-style I2C driver for most common 8 and 16 bit I2C based "quasi-bidirectional" GPIO expanders: pcf8574 or pcf8575, and several compatible models (mostly faster, supporting I2C at up to 1 MHz). The driver exposes the GPIO signals using the platform-neutral GPIO programming interface, so they are easily accessed by other kernel code. The lack of such a flexible kernel API has been a big factor in the proliferation of board-specific drivers for these chips... stuff that rarely makes it upstream since it's so ugly. This driver will let such boards use standard calls. Since it's a new-style driver, these devices must be configured as part of board-specific init. That eliminates the need for error-prone manual configuration of module parameters, and makes compatibility with legacy drivers (pcf8574.c, pc8575.c) for these chips easier (there's a clear either/or disjunction). Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Acked-by: Jean Delvare <khali@linux-fr.org> Cc: Eric Miao <eric.miao@marvell.com> Cc: Sam Ravnborg <sam@ravnborg.org> Cc: Haavard Skinnemoen <hskinnemoen@atmel.com> Cc: Philipp Zabel <philipp.zabel@gmail.com> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Ben Gardner <bgardner@wabtec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05gpiolib support for the PXA architecturePhilipp Zabel2-28/+33
This adds gpiolib support for the PXA architecture: - move all GPIO API functions from generic.c into gpio.c - convert the gpio_get/set_value macros into inline functions This makes it easier to hook up GPIOs provided by external chips like ASICs and CPLDs. Signed-off-by: Philipp Zabel <philipp.zabel@gmail.com> Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Acked-by: Russell King <rmk+kernel@arm.linux.org.uk> Cc: Jean Delvare <khali@linux-fr.org> Cc: Eric Miao <eric.miao@marvell.com> Cc: Sam Ravnborg <sam@ravnborg.org> Cc: Haavard Skinnemoen <hskinnemoen@atmel.com> Cc: Ben Gardner <bgardner@wabtec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> [ Minor ARM fixup from David Brownell folded into this ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05gpiolib: add gpio provider infrastructureDavid Brownell1-0/+98
Provide new implementation infrastructure that platforms may choose to use when implementing the GPIO programming interface. Platforms can update their GPIO support to use this. In many cases the incremental cost to access a non-inlined GPIO should be less than a dozen instructions, with the memory cost being about a page (total) of extra data and code. The upside is: * Providing two features which were "want to have (but OK to defer)" when GPIO interfaces were first discussed in November 2006: - A "struct gpio_chip" to plug in GPIOs that aren't directly supported by SOC platforms, but come from FPGAs or other multifunction devices using conventional device registers (like UCB-1x00 or SM501 GPIOs, and southbridges in PCs with more open specs than usual). - Full support for message-based GPIO expanders, where registers are accessed through sleeping I/O calls. Previous support for these "cansleep" calls was just stubs. (One example: the widely used pcf8574 I2C chips, with 8 GPIOs each.) * Including a non-stub implementation of the gpio_{request,free}() calls, making those calls much more useful. The diagnostic labels are also recorded given DEBUG_FS, so /sys/kernel/debug/gpio can show a snapshot of all GPIOs known to this infrastructure. The driver programming interfaces introduced in 2.6.21 do not change at all; this infrastructure is entirely below those covers. Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Cc: Sam Ravnborg <sam@ravnborg.org> Cc: Jean Delvare <khali@linux-fr.org> Cc: Eric Miao <eric.miao@marvell.com> Cc: Haavard Skinnemoen <hskinnemoen@atmel.com> Cc: Philipp Zabel <philipp.zabel@gmail.com> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Ben Gardner <bgardner@wabtec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05iommu sg merging: PCI: add dma segment boundary supportFUJITA Tomonori1-0/+7
This adds PCI's accessor for segment_boundary_mask in device_dma_parameters. The default segment_boundary is set to 0xffffffff, same to the block layer's default value (and the scsi mid layer uses the same value). Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Cc: James Bottomley <James.Bottomley@steeleye.com> Cc: Jens Axboe <jens.axboe@oracle.com> Cc: Greg KH <greg@kroah.com> Cc: Jeff Garzik <jeff@garzik.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05iommu sg merging: add accessors for segment_boundary_mask in ↵FUJITA Tomonori1-0/+15
device_dma_parameters() This adds new accessors for segment_boundary_mask in device_dma_parameters structure in the same way I did for max_segment_size. So we can easily change where to place struct device_dma_parameters in the future. dma_get_segment boundary returns 0xffffffff if dma_parms in struct device isn't set up properly. 0xffffffff is the default value used in the block layer and the scsi mid layer. Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Cc: James Bottomley <James.Bottomley@steeleye.com> Cc: Jens Axboe <jens.axboe@oracle.com> Cc: Greg KH <greg@kroah.com> Cc: Jeff Garzik <jeff@garzik.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05iommu sg: kill __clear_bit_string and find_next_zero_stringFUJITA Tomonori1-16/+0
This kills unused __clear_bit_string and find_next_zero_string (they were used by only gart and calgary IOMMUs). Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Cc: Jeff Garzik <jeff@garzik.org> Cc: James Bottomley <James.Bottomley@steeleye.com> Cc: Jens Axboe <jens.axboe@oracle.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@elte.hu> Cc: Muli Ben-Yehuda <mulix@mulix.org> Cc: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05iommu sg: powerpc: convert iommu to use the IOMMU helperFUJITA Tomonori1-5/+5
This patch converts PPC's IOMMU to use the IOMMU helper functions. The IOMMU doesn't allocate a memory area spanning LLD's segment boundary anymore. iseries_hv_alloc and iseries_hv_map don't have proper device struct. 4GB boundary is used for them. Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Cc: Jeff Garzik <jeff@garzik.org> Cc: James Bottomley <James.Bottomley@steeleye.com> Cc: Jens Axboe <jens.axboe@oracle.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05iommu sg: add IOMMU helper functions for the free area managementFUJITA Tomonori1-0/+7
This adds IOMMU helper functions for the free area management. These functions take care of LLD's segment boundary limit for IOMMUs. They would be useful for IOMMUs that use bitmap for the free area management. Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Cc: Jeff Garzik <jeff@garzik.org> Cc: James Bottomley <James.Bottomley@steeleye.com> Cc: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05iommu sg merging: alpha: make pci_iommu respect the segment size limitsFUJITA Tomonori1-0/+1
This patch makes pci_iommu respect segment size limits when merging sg lists. Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Cc: Jeff Garzik <jeff@garzik.org> Cc: James Bottomley <James.Bottomley@steeleye.com> Acked-by: Jens Axboe <jens.axboe@oracle.com> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05iommu sg merging: ppc: make iommu respect the segment size limitsFUJITA Tomonori1-1/+1
This patch makes iommu respect segment size limits when merging sg lists. Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Cc: Jeff Garzik <jeff@garzik.org> Cc: James Bottomley <James.Bottomley@steeleye.com> Acked-by: Jens Axboe <jens.axboe@oracle.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05iommu sg merging: PCI: add device_dma_parameters supportFUJITA Tomonori1-0/+9
This adds struct device_dma_parameters in struct pci_dev and properly sets up a pointer in struct device. The default max_segment_size is set to 64K, same to the block layer's default value. Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Mostly-acked-by: Jeff Garzik <jeff@garzik.org> Cc: James Bottomley <James.Bottomley@steeleye.com> Acked-by: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05iommu sg merging: add device_dma_parameters structureFUJITA Tomonori2-0/+26
IOMMUs merges scatter/gather segments without considering a low level driver's restrictions. The problem is that IOMMUs can't access to the limitations because they are in request_queue. This patchset introduces a new structure, device_dma_parameters, including dma information. A pointer to device_dma_parameters is added to struct device. The bus specific structures (like pci_dev) includes device_dma_parameters. Low level drivers can use dma_set_max_seg_size to tell IOMMUs about the restrictions. We can move more dma stuff in struct device (like dma_mask) to struct device_dma_parameters later (needs some cleanups before that). This includes patches for all the IOMMUs that could merge sg (x86_64, ppc, IA64, alpha, sparc64, and parisc) though only the ppc patch was tested. The patches for other IOMMUs are only compile tested. This patch: Add a new structure, device_dma_parameters, including dma information. A pointer to device_dma_parameters is added to struct device. - there are only max_segment_size and segment_boundary_mask there but we'll move more dma stuff in struct device (like dma_mask) to struct device_dma_parameters later. segment_boundary_mask is not supported yet. - new accessors for the dma parameters are added. So we can easily change where to place struct device_dma_parameters in the future. - dma_get_max_seg_size returns 64K if dma_parms in struct device isn't set up properly. 64K is the default max_segment_size in the block layer. Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Acked-by: Jeff Garzik <jeff@garzik.org> Cc: James Bottomley <James.Bottomley@steeleye.com> Acked-by: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-058250.c: support specifying DW APB UARTs in device platform_dataWill Newton1-0/+1
Allow the private_data field to be specified in platform_data for the standard 8250/16550 UART. This field is used by DW APB type UARTs and without this patch it's only possible to set this field when registering the port by hand. If private_data is not set then the driver will potentially oops with a NULL pointer dereference. Signed-off-by: Will Newton <will.newton@gmail.com> Acked-by: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Russell King <rmk@arm.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05serial: add ADDI-DATA GmbH Communication cardsin8250_pci.c and pci_ids.hKrauth.Julien1-0/+17
Add ADDI-DATA GmbH communication cards to 8250_pci driver. Supported cards are: APCI-7300, APCI-7420, APCI-7500, APCI-7800 APCI-7300-2, APCI-7420-2, APCI-7500-2 APCI-7300-3, APCI-7420-3, APCI-7500-3, APCI-7800-3 [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Krauth J. <krauth.julien@addi-data.com> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Alan Cox <alan@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05pcmcia: replace kio_addr_t with unsigned int everywhereOlof Johansson2-4/+3
Remove kio_addr_t, and replace it with unsigned int. No known architecture needs more than 32 bits for IO addresses and ports and having a separate type for it is just messy. Signed-off-by: Olof Johansson <olof@lixom.net> Cc: Christoph Hellwig <hch@lst.de> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Dominik Brodowski <linux@dominikbrodowski.net> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05pcmcia: convert some internal-only ioaddr_t to unsigned intOlof Johansson1-4/+4
Convert the io_req_t members to unsigned int, to allow use on machines with more than 16 bits worth of IO ports (i.e. secondary busses on ppc64, etc). There was only a couple of places in drivers where a change was needed. I left printk formats alone (there are lots of %04x-style formats in there), mostly to not change the format on the platforms that only have 16-bit io addresses, but also because the padding doesn't really add all that much value most of the time. I found only one sprintf of an address, and upsized the string accordingly (I doubt anyone will have anywhere near INT_MAX as irq value, but at least there's room for it now). Signed-off-by: Olof Johansson <olof@lixom.net> Cc: Christoph Hellwig <hch@lst.de> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Dominik Brodowski <linux@dominikbrodowski.net> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05m32r: remove dead config symbols from M32R codeJiri Olsa2-4/+2
remove dead config symbols from M32R code Signed-off-by: Jiri Olsa <olsajiri@gmail.com> Cc: Hirokazu Takata <takata@linux-m32r.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05include/asm-powerpc/nvram.h needs list.hAndrew Morton1-0/+3
CC [M] sound/ppc/awacs.o In file included from sound/ppc/awacs.c:24: include/asm/nvram.h:62: error: field 'partition' has incomplete type Reported-by: Mariusz Kozlowski <m.kozlowski@tuxland.pl> Cc: Paul Mackerras <paulus@samba.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05sdio: fix module device table definition for m68kAl Viro1-1/+2
FATAL: drivers/bluetooth/btsdio: sizeof(struct sdio_device_id)=12 is not a modulo of the size of section __mod_sdio_device_table=30. Fix definition of struct sdio_device_id in mod_devicetable.h m68k has 16bit alignment for unsigned long. Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Sam Ravnborg <sam@ravnborg.org> Cc: Pierre Ossman <drzeus@drzeus.cx> CC: Marcel Holtmann <marcel@holtmann.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05timerfd: wire the new timerfd API to the x86 familyDavide Libenzi2-3/+10
Wires up the new timerfd API to the x86 family. Signed-off-by: Davide Libenzi <davidel@xmailserver.org> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: <linux-arch@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05timerfd: new timerfd APIDavide Libenzi4-10/+16
This is the new timerfd API as it is implemented by the following patch: int timerfd_create(int clockid, int flags); int timerfd_settime(int ufd, int flags, const struct itimerspec *utmr, struct itimerspec *otmr); int timerfd_gettime(int ufd, struct itimerspec *otmr); The timerfd_create() API creates an un-programmed timerfd fd. The "clockid" parameter can be either CLOCK_MONOTONIC or CLOCK_REALTIME. The timerfd_settime() API give new settings by the timerfd fd, by optionally retrieving the previous expiration time (in case the "otmr" parameter is not NULL). The time value specified in "utmr" is absolute, if the TFD_TIMER_ABSTIME bit is set in the "flags" parameter. Otherwise it's a relative time. The timerfd_gettime() API returns the next expiration time of the timer, or {0, 0} if the timerfd has not been set yet. Like the previous timerfd API implementation, read(2) and poll(2) are supported (with the same interface). Here's a simple test program I used to exercise the new timerfd APIs: http://www.xmailserver.org/timerfd-test2.c [akpm@linux-foundation.org: coding-style cleanups] [akpm@linux-foundation.org: fix ia64 build] [akpm@linux-foundation.org: fix m68k build] [akpm@linux-foundation.org: fix mips build] [akpm@linux-foundation.org: fix alpha, arm, blackfin, cris, m68k, s390, sparc and sparc64 builds] [heiko.carstens@de.ibm.com: fix s390] [akpm@linux-foundation.org: fix powerpc build] [akpm@linux-foundation.org: fix sparc64 more] Signed-off-by: Davide Libenzi <davidel@xmailserver.org> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Davide Libenzi <davidel@xmailserver.org> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Davide Libenzi <davidel@xmailserver.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05timerfd: introduce a new hrtimer_forward_now() functionDavide Libenzi1-0/+7
I think that advancing the timer against the timer's current "now" can be a pretty common usage, so, w/out exposing hrtimer's internals, we add a new hrtimer_forward_now() function. Signed-off-by: Davide Libenzi <davidel@xmailserver.org> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05exec: rework the group exit and fix the race with killOleg Nesterov1-0/+7
As Roland pointed out, we have the very old problem with exec. de_thread() sets SIGNAL_GROUP_EXIT, kills other threads, changes ->group_leader and then clears signal->flags. All signals (even fatal ones) sent in this window (which is not too small) will be lost. With this patch exec doesn't abuse SIGNAL_GROUP_EXIT. signal_group_exit(), the new helper, should be used to detect exit_group() or exec() in progress. It can have more users, but this patch does only strictly necessary changes. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Cc: Davide Libenzi <davidel@xmailserver.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Robin Holt <holt@sgi.com> Cc: Roland McGrath <roland@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05get_task_comm(): return the resultAndrew Morton1-1/+1
It was dumb to make get_task_comm() return void. Change it to return a pointer to the resulting output for caller convenience. Cc: Ulrich Drepper <drepper@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Roland McGrath <roland@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05lockdep: annotate epollPeter Zijlstra1-0/+16
On Sat, 2008-01-05 at 13:35 -0800, Davide Libenzi wrote: > I remember I talked with Arjan about this time ago. Basically, since 1) > you can drop an epoll fd inside another epoll fd 2) callback-based wakeups > are used, you can see a wake_up() from inside another wake_up(), but they > will never refer to the same lock instance. > Think about: > > dfd = socket(...); > efd1 = epoll_create(); > efd2 = epoll_create(); > epoll_ctl(efd1, EPOLL_CTL_ADD, dfd, ...); > epoll_ctl(efd2, EPOLL_CTL_ADD, efd1, ...); > > When a packet arrives to the device underneath "dfd", the net code will > issue a wake_up() on its poll wake list. Epoll (efd1) has installed a > callback wakeup entry on that queue, and the wake_up() performed by the > "dfd" net code will end up in ep_poll_callback(). At this point epoll > (efd1) notices that it may have some event ready, so it needs to wake up > the waiters on its poll wait list (efd2). So it calls ep_poll_safewake() > that ends up in another wake_up(), after having checked about the > recursion constraints. That are, no more than EP_MAX_POLLWAKE_NESTS, to > avoid stack blasting. Never hit the same queue, to avoid loops like: > > epoll_ctl(efd2, EPOLL_CTL_ADD, efd1, ...); > epoll_ctl(efd3, EPOLL_CTL_ADD, efd2, ...); > epoll_ctl(efd4, EPOLL_CTL_ADD, efd3, ...); > epoll_ctl(efd1, EPOLL_CTL_ADD, efd4, ...); > > The code "if (tncur->wq == wq || ..." prevents re-entering the same > queue/lock. Since the epoll code is very careful to not nest same instance locks allow the recursion. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Tested-by: Stefan Richter <stefanr@s5r6.in-berlin.de> Acked-by: Davide Libenzi <davidel@xmailserver.org> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-04Merge branch 'for-linus' of master.kernel.org:/home/rmk/linux-2.6-armLinus Torvalds30-318/+661
* 'for-linus' of master.kernel.org:/home/rmk/linux-2.6-arm: (44 commits) [ARM] 4822/1: RealView: Change the REALVIEW_MPCORE configuration option [ARM] 4821/1: RealView: Remove the platform dependencies from localtimer.c [ARM] 4820/1: RealView: Select the timer IRQ at run-time [ARM] 4819/1: RealView: Fix entry-macro.S to work with multiple platforms [ARM] 4818/1: RealView: Add core-tile detection [ARM] 4817/1: RealView: Move the AMBA resource definitions to realview_eb.c [ARM] 4816/1: RealView: Move the platform-specific definitions into board-eb.h [ARM] 4815/1: RealView: Add clockevents suport for the local timers [ARM] 4814/1: RealView: Add broadcasting clockevents support for ARM11MPCore [ARM] 4813/1: Add SMP helper functions for clockevents support [ARM] 4812/1: RealView: clockevents support for the RealView platforms [ARM] 4811/1: RealView: clocksource support for the RealView platforms [ARM] 4736/1: Export atags to userspace and allow kexec to use customised atags [ARM] 4798/1: pcm027: fix missing header file [ARM] 4803/1: pxa: fix building issue of poodle.c caused by patch 4737/1 [ARM] 4801/1: pxa: fix building issues of missing pxa2xx-regs.h [ARM] pxa: introduce sysdev for pxa3xx static memory controller [ARM] pxa: add preliminary suspend/resume code for pxa3xx [ARM] pxa: introduce sysdev for GPIO register saving/restoring [ARM] pxa: introduce sysdev for IRQ register saving/restoring ...
2008-02-04Merge branch 'slub-linus' of ↵Linus Torvalds1-6/+9
git://git.kernel.org/pub/scm/linux/kernel/git/christoph/vm * 'slub-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/christoph/vm: Explain kmem_cache_cpu fields SLUB: Do not upset lockdep SLUB: Fix coding style violations Add parameter to add_partial to avoid having two functions SLUB: rename defrag to remote_node_defrag_ratio Move count_partial before kmem_cache_shrink SLUB: Fix sysfs refcounting slub: fix shadowed variable sparse warnings
2008-02-04Explain kmem_cache_cpu fieldsChristoph Lameter1-5/+5
Add some comments explaining the fields of the kmem_cache_cpu structure. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>