diff options
Diffstat (limited to 'fs/proc/vmcore.c')
| -rw-r--r-- | fs/proc/vmcore.c | 41 |
1 files changed, 22 insertions, 19 deletions
diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c index 702754dd1daf..edeb01dfe05d 100644 --- a/fs/proc/vmcore.c +++ b/fs/proc/vmcore.c @@ -62,7 +62,8 @@ core_param(novmcoredd, vmcoredd_disabled, bool, 0); /* Device Dump Size */ static size_t vmcoredd_orig_sz; -static DECLARE_RWSEM(vmcore_cb_rwsem); +static DEFINE_SPINLOCK(vmcore_cb_lock); +DEFINE_STATIC_SRCU(vmcore_cb_srcu); /* List of registered vmcore callbacks. */ static LIST_HEAD(vmcore_cb_list); /* Whether the vmcore has been opened once. */ @@ -70,8 +71,8 @@ static bool vmcore_opened; void register_vmcore_cb(struct vmcore_cb *cb) { - down_write(&vmcore_cb_rwsem); INIT_LIST_HEAD(&cb->next); + spin_lock(&vmcore_cb_lock); list_add_tail(&cb->next, &vmcore_cb_list); /* * Registering a vmcore callback after the vmcore was opened is @@ -79,14 +80,14 @@ void register_vmcore_cb(struct vmcore_cb *cb) */ if (vmcore_opened) pr_warn_once("Unexpected vmcore callback registration\n"); - up_write(&vmcore_cb_rwsem); + spin_unlock(&vmcore_cb_lock); } EXPORT_SYMBOL_GPL(register_vmcore_cb); void unregister_vmcore_cb(struct vmcore_cb *cb) { - down_write(&vmcore_cb_rwsem); - list_del(&cb->next); + spin_lock(&vmcore_cb_lock); + list_del_rcu(&cb->next); /* * Unregistering a vmcore callback after the vmcore was opened is * very unusual (e.g., forced driver removal), but we cannot stop @@ -94,7 +95,9 @@ void unregister_vmcore_cb(struct vmcore_cb *cb) */ if (vmcore_opened) pr_warn_once("Unexpected vmcore callback unregistration\n"); - up_write(&vmcore_cb_rwsem); + spin_unlock(&vmcore_cb_lock); + + synchronize_srcu(&vmcore_cb_srcu); } EXPORT_SYMBOL_GPL(unregister_vmcore_cb); @@ -103,9 +106,8 @@ static bool pfn_is_ram(unsigned long pfn) struct vmcore_cb *cb; bool ret = true; - lockdep_assert_held_read(&vmcore_cb_rwsem); - - list_for_each_entry(cb, &vmcore_cb_list, next) { + list_for_each_entry_srcu(cb, &vmcore_cb_list, next, + srcu_read_lock_held(&vmcore_cb_srcu)) { if (unlikely(!cb->pfn_is_ram)) continue; ret = cb->pfn_is_ram(cb, pfn); @@ -118,9 +120,9 @@ static bool pfn_is_ram(unsigned long pfn) static int open_vmcore(struct inode *inode, struct file *file) { - down_read(&vmcore_cb_rwsem); + spin_lock(&vmcore_cb_lock); vmcore_opened = true; - up_read(&vmcore_cb_rwsem); + spin_unlock(&vmcore_cb_lock); return 0; } @@ -133,6 +135,7 @@ ssize_t read_from_oldmem(char *buf, size_t count, unsigned long pfn, offset; size_t nr_bytes; ssize_t read = 0, tmp; + int idx; if (!count) return 0; @@ -140,7 +143,7 @@ ssize_t read_from_oldmem(char *buf, size_t count, offset = (unsigned long)(*ppos % PAGE_SIZE); pfn = (unsigned long)(*ppos / PAGE_SIZE); - down_read(&vmcore_cb_rwsem); + idx = srcu_read_lock(&vmcore_cb_srcu); do { if (count > (PAGE_SIZE - offset)) nr_bytes = PAGE_SIZE - offset; @@ -165,7 +168,7 @@ ssize_t read_from_oldmem(char *buf, size_t count, offset, userbuf); } if (tmp < 0) { - up_read(&vmcore_cb_rwsem); + srcu_read_unlock(&vmcore_cb_srcu, idx); return tmp; } @@ -176,8 +179,8 @@ ssize_t read_from_oldmem(char *buf, size_t count, ++pfn; offset = 0; } while (count); + srcu_read_unlock(&vmcore_cb_srcu, idx); - up_read(&vmcore_cb_rwsem); return read; } @@ -568,18 +571,18 @@ static int vmcore_remap_oldmem_pfn(struct vm_area_struct *vma, unsigned long from, unsigned long pfn, unsigned long size, pgprot_t prot) { - int ret; + int ret, idx; /* - * Check if oldmem_pfn_is_ram was registered to avoid - * looping over all pages without a reason. + * Check if a callback was registered to avoid looping over all + * pages without a reason. */ - down_read(&vmcore_cb_rwsem); + idx = srcu_read_lock(&vmcore_cb_srcu); if (!list_empty(&vmcore_cb_list)) ret = remap_oldmem_pfn_checked(vma, from, pfn, size, prot); else ret = remap_oldmem_pfn_range(vma, from, pfn, size, prot); - up_read(&vmcore_cb_rwsem); + srcu_read_unlock(&vmcore_cb_srcu, idx); return ret; } |