diff options
author | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2011-03-03 17:56:07 +0100 |
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committer | Martin Schwidefsky <sky@mschwide.boeblingen.de.ibm.com> | 2011-03-03 17:56:14 +0100 |
commit | 0c2bd9b24e73287aa4ee87844c847205e0da8a9b (patch) | |
tree | 4e56fae8cb7f8dcbc022771436e573c5c12b94fb /drivers/s390/char/tape_3590.c | |
parent | b652277b09d3d030cb074cc6a98ba80b34244c03 (diff) |
[S390] tape: deadlock on system work queue
The 34xx and 3590 tape driver uses the system work queue to defer work
from the interrupt function to process context, e.g. a medium sense
after an unsolicited interrupt. The tape commands started by the work
handler need to be asynchronous, otherwise a deadlock on the system
work queue can occur.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'drivers/s390/char/tape_3590.c')
-rw-r--r-- | drivers/s390/char/tape_3590.c | 83 |
1 files changed, 67 insertions, 16 deletions
diff --git a/drivers/s390/char/tape_3590.c b/drivers/s390/char/tape_3590.c index fbe361fcd2c0..de2e99e0a71b 100644 --- a/drivers/s390/char/tape_3590.c +++ b/drivers/s390/char/tape_3590.c @@ -329,17 +329,17 @@ out: /* * Enable encryption */ -static int tape_3592_enable_crypt(struct tape_device *device) +static struct tape_request *__tape_3592_enable_crypt(struct tape_device *device) { struct tape_request *request; char *data; DBF_EVENT(6, "tape_3592_enable_crypt\n"); if (!crypt_supported(device)) - return -ENOSYS; + return ERR_PTR(-ENOSYS); request = tape_alloc_request(2, 72); if (IS_ERR(request)) - return PTR_ERR(request); + return request; data = request->cpdata; memset(data,0,72); @@ -354,23 +354,42 @@ static int tape_3592_enable_crypt(struct tape_device *device) request->op = TO_CRYPT_ON; tape_ccw_cc(request->cpaddr, MODE_SET_CB, 36, data); tape_ccw_end(request->cpaddr + 1, MODE_SET_CB, 36, data + 36); + return request; +} + +static int tape_3592_enable_crypt(struct tape_device *device) +{ + struct tape_request *request; + + request = __tape_3592_enable_crypt(device); + if (IS_ERR(request)) + return PTR_ERR(request); return tape_do_io_free(device, request); } +static void tape_3592_enable_crypt_async(struct tape_device *device) +{ + struct tape_request *request; + + request = __tape_3592_enable_crypt(device); + if (!IS_ERR(request)) + tape_do_io_async_free(device, request); +} + /* * Disable encryption */ -static int tape_3592_disable_crypt(struct tape_device *device) +static struct tape_request *__tape_3592_disable_crypt(struct tape_device *device) { struct tape_request *request; char *data; DBF_EVENT(6, "tape_3592_disable_crypt\n"); if (!crypt_supported(device)) - return -ENOSYS; + return ERR_PTR(-ENOSYS); request = tape_alloc_request(2, 72); if (IS_ERR(request)) - return PTR_ERR(request); + return request; data = request->cpdata; memset(data,0,72); @@ -383,9 +402,28 @@ static int tape_3592_disable_crypt(struct tape_device *device) tape_ccw_cc(request->cpaddr, MODE_SET_CB, 36, data); tape_ccw_end(request->cpaddr + 1, MODE_SET_CB, 36, data + 36); + return request; +} + +static int tape_3592_disable_crypt(struct tape_device *device) +{ + struct tape_request *request; + + request = __tape_3592_disable_crypt(device); + if (IS_ERR(request)) + return PTR_ERR(request); return tape_do_io_free(device, request); } +static void tape_3592_disable_crypt_async(struct tape_device *device) +{ + struct tape_request *request; + + request = __tape_3592_disable_crypt(device); + if (!IS_ERR(request)) + tape_do_io_async_free(device, request); +} + /* * IOCTL: Set encryption status */ @@ -457,8 +495,7 @@ tape_3590_ioctl(struct tape_device *device, unsigned int cmd, unsigned long arg) /* * SENSE Medium: Get Sense data about medium state */ -static int -tape_3590_sense_medium(struct tape_device *device) +static int tape_3590_sense_medium(struct tape_device *device) { struct tape_request *request; @@ -470,6 +507,18 @@ tape_3590_sense_medium(struct tape_device *device) return tape_do_io_free(device, request); } +static void tape_3590_sense_medium_async(struct tape_device *device) +{ + struct tape_request *request; + + request = tape_alloc_request(1, 128); + if (IS_ERR(request)) + return; + request->op = TO_MSEN; + tape_ccw_end(request->cpaddr, MEDIUM_SENSE, 128, request->cpdata); + tape_do_io_async_free(device, request); +} + /* * MTTELL: Tell block. Return the number of block relative to current file. */ @@ -546,15 +595,14 @@ tape_3590_read_opposite(struct tape_device *device, * 2. The attention msg is written to the "read subsystem data" buffer. * In this case we probably should print it to the console. */ -static int -tape_3590_read_attmsg(struct tape_device *device) +static void tape_3590_read_attmsg_async(struct tape_device *device) { struct tape_request *request; char *buf; request = tape_alloc_request(3, 4096); if (IS_ERR(request)) - return PTR_ERR(request); + return; request->op = TO_READ_ATTMSG; buf = request->cpdata; buf[0] = PREP_RD_SS_DATA; @@ -562,12 +610,15 @@ tape_3590_read_attmsg(struct tape_device *device) tape_ccw_cc(request->cpaddr, PERFORM_SS_FUNC, 12, buf); tape_ccw_cc(request->cpaddr + 1, READ_SS_DATA, 4096 - 12, buf + 12); tape_ccw_end(request->cpaddr + 2, NOP, 0, NULL); - return tape_do_io_free(device, request); + tape_do_io_async_free(device, request); } /* * These functions are used to schedule follow-up actions from within an * interrupt context (like unsolicited interrupts). + * Note: the work handler is called by the system work queue. The tape + * commands started by the handler need to be asynchrounous, otherwise + * a deadlock can occur e.g. in case of a deferred cc=1 (see __tape_do_irq). */ struct work_handler_data { struct tape_device *device; @@ -583,16 +634,16 @@ tape_3590_work_handler(struct work_struct *work) switch (p->op) { case TO_MSEN: - tape_3590_sense_medium(p->device); + tape_3590_sense_medium_async(p->device); break; case TO_READ_ATTMSG: - tape_3590_read_attmsg(p->device); + tape_3590_read_attmsg_async(p->device); break; case TO_CRYPT_ON: - tape_3592_enable_crypt(p->device); + tape_3592_enable_crypt_async(p->device); break; case TO_CRYPT_OFF: - tape_3592_disable_crypt(p->device); + tape_3592_disable_crypt_async(p->device); break; default: DBF_EVENT(3, "T3590: work handler undefined for " |