When we tear down a device we try to flush all outstanding commands in scsi_free_queue(). However the check in scsi_request_fn() is imperfect as it only signals that we _might start_ aborting commands, not that we've actually aborted some. So move the printk inside the scsi_kill_request function, this will also give us a hint about which commands are aborted. Signed-off-by: Hannes Reinecke <hare@suse.de> Signed-off-by: James Bottomley <JBottomley@Parallels.com>
* 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux: (230 commits)
Revert "tracing: Include module.h in define_trace.h"
irq: don't put module.h into irq.h for tracking irqgen modules.
bluetooth: macroize two small inlines to avoid module.h
ip_vs.h: fix implicit use of module_get/module_put from module.h
nf_conntrack.h: fix up fallout from implicit moduleparam.h presence
include: replace linux/module.h with "struct module" wherever possible
include: convert various register fcns to macros to avoid include chaining
crypto.h: remove unused crypto_tfm_alg_modname() inline
uwb.h: fix implicit use of asm/page.h for PAGE_SIZE
pm_runtime.h: explicitly requires notifier.h
linux/dmaengine.h: fix implicit use of bitmap.h and asm/page.h
miscdevice.h: fix up implicit use of lists and types
stop_machine.h: fix implicit use of smp.h for smp_processor_id
of: fix implicit use of errno.h in include/linux/of.h
of_platform.h: delete needless include <linux/module.h>
acpi: remove module.h include from platform/aclinux.h
miscdevice.h: delete unnecessary inclusion of module.h
device_cgroup.h: delete needless include <linux/module.h>
net: sch_generic remove redundant use of <linux/module.h>
net: inet_timewait_sock doesnt need <linux/module.h>
...
Fix up trivial conflicts (other header files, and removal of the ab3550 mfd driver) in
- drivers/media/dvb/frontends/dibx000_common.c
- drivers/media/video/{mt9m111.c,ov6650.c}
- drivers/mfd/ab3550-core.c
- include/linux/dmaengine.h
For the basic SCSI infrastructure files that are exporting symbols but not modules themselves, add in the basic export.h header file to allow the exports. Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Make sure that SCSI device removal via scsi_remove_host() does finish all pending SCSI commands. Currently that's not the case and hence removal of a SCSI host during I/O can cause a deadlock. See also "blkdev_issue_discard() hangs forever if underlying storage device is removed" (http://bugzilla.kernel.org/show_bug.cgi?id=40472). See also http://lkml.org/lkml/2011/8/27/6. Signed-off-by: Bart Van Assche <bvanassche@acm.org> Cc: <stable@kernel.org> Signed-off-by: James Bottomley <JBottomley@Parallels.com>
During cable pull tests on our 16G FC adapter, we are seeing errors, typically reads to close targets, which fail due to CRC or framing errors caused by the cable being pull (return status DID_ERROR). The adapter detects the error on one of the first frames received, marks the FC exchange as dead (further frames go to bit bucket) and signals the host of the error. This action is so quick, and coupled with fast host CPUs, creates a scenario in which the midlayer sees the failure and retries the io almost immediately. We've seen link traces with the retry on the link while the original i/o is still being processed by the target. We're also seeing the time window for the "link to pull-apart" and the physical interface to report disconnected to be in the few millisecond range. Which means, we're encountering scenarios where the full retry count is exhausted (all with error) by the midlayer before the link disconnect state is detected. We looked at 8G FC behavior and occasionally see the same behavior, but as the link was slower, it rarely could exhaust all retries before the link reported disconnect. What is needed is a slight delay between io retries due to DID_ERROR to cover this error. It is inappropriate to put this delay in the driver, as the error is indistinguishable from other link-related errors, nor does the driver track whether the io is a retry or not. This is also easier than tracking between-io-error bursts that are seen in this scenario. The patch below updates the retry path so that it inserts a delay as if the target was busy. The busy delay is on the order of 6ms. This delay is sufficient to ensure the link down condition is reported before the retry count is exhausted (at most 1 retry is seen). Signed-off-by: Alex Iannicelli <alex.iannicelli@emulex.com> Signed-off-by: James Smart <james.smart@emulex.com> Signed-off-by: James Bottomley <JBottomley@Parallels.com>
USB surprise removal of sr is triggering an oops in scsi_dispatch_command(). What seems to be happening is that USB is hanging on to a queue reference until the last close of the upper device, so the crash is caused by surprise remove of a mounted CD followed by attempted unmount. The problem is that USB doesn't issue its final commands as part of the SCSI teardown path, but on last close when the block queue is long gone. The long term fix is probably to make sr do the teardown in the same way as sd (so remove all the lower bits on ejection, but keep the upper disk alive until last close of user space). However, the current oops can be simply fixed by not allowing any commands to be sent to a dead queue. Cc: stable@kernel.org Signed-off-by: James Bottomley <JBottomley@Parallels.com>
* 'for-linus' of git://git.kernel.dk/linux-2.6-block: block: don't delay blk_run_queue_async scsi: remove performance regression due to async queue run blk-throttle: Use task_subsys_state() to determine a task's blkio_cgroup block: rescan partitions on invalidated devices on -ENOMEDIA too cdrom: always check_disk_change() on open block: unexport DISK_EVENT_MEDIA_CHANGE for legacy/fringe drivers
Commit c21e6beb removed our queue request_fn re-enter
protection, and defaulted to always running the queues from
kblockd to be safe. This was a known potential slow down,
but should be safe.
Unfortunately this is causing big performance regressions for
some, so we need to improve this logic. Looking into the details
of the re-enter, the real issue is on requeue of requests.
Requeue of requests upon seeing a BUSY condition from the device
ends up re-running the queue, causing traces like this:
scsi_request_fn()
scsi_dispatch_cmd()
scsi_queue_insert()
__scsi_queue_insert()
scsi_run_queue()
scsi_request_fn()
...
potentially causing the issue we want to avoid. So special
case the requeue re-run of the queue, but improve it to offload
the entire run of local queue and starved queue from a single
workqueue callback. This is a lot better than potentially
kicking off a workqueue run for each device seen.
This also fixes the issue of the local device going into recursion,
since the above mentioned commit never moved that queue run out
of line.
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
The recent commit closing the race window in device teardown:
commit 86cbfb5607d4b81b1a993ff689bbd2addd5d3a9b
Author: James Bottomley <James.Bottomley@suse.de>
Date: Fri Apr 22 10:39:59 2011 -0500
[SCSI] put stricter guards on queue dead checks
is causing a potential NULL deref in scsi_run_queue() because the
q->queuedata may already be NULL by the time this function is called.
Since we shouldn't be running a queue that is being torn down, simply
add a NULL check in scsi_run_queue() to forestall this.
Tested-by: Jim Schutt <jaschut@sandia.gov>
Cc: stable@kernel.org
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
We are currently using this flag to check whether it's safe to call into ->request_fn(). If it is set, we punt to kblockd. But we get a lot of false positives and excessive punts to kblockd, which hurts performance. The only real abuser of this infrastructure is SCSI. So export the async queue run and convert SCSI over to use that. There's room for improvement in that SCSI need not always use the async call, but this fixes our performance issue and they can fix that up in due time. Signed-off-by: Jens Axboe <jaxboe@fusionio.com>