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Groups > linux.kernel > #1258193

[PATCH 3.12 018/123] scsi: fix scsi_error_handler vs. scsi_host_dev_release race

From Jiri Slaby <jslaby@suse.cz>
Newsgroups linux.kernel
Subject [PATCH 3.12 018/123] scsi: fix scsi_error_handler vs. scsi_host_dev_release race
Date 2015-10-28 15:40 +0100
Message-ID <qoA3p-3Pi-39@gated-at.bofh.it> (permalink)
References <qozqF-3k6-9@gated-at.bofh.it>
Organization linux.* mail to news gateway

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From: Michal Hocko <mhocko@suse.com>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

commit 537b604c8b3aa8b96fe35f87dd085816552e294c upstream.

b9d5c6b7ef57 ("[SCSI] cleanup setting task state in
scsi_error_handler()") has introduced a race between scsi_error_handler
and scsi_host_dev_release resulting in the hang when the device goes
away because scsi_error_handler might miss a wake up:

CPU0					CPU1
scsi_error_handler			scsi_host_dev_release
  					  kthread_stop()
  kthread_should_stop()
    test_bit(KTHREAD_SHOULD_STOP)
					    set_bit(KTHREAD_SHOULD_STOP)
					    wake_up_process()
					    wait_for_completion()

  set_current_state(TASK_INTERRUPTIBLE)
  schedule()

The most straightforward solution seems to be to invert the ordering of
the set_current_state and kthread_should_stop.

The issue has been noticed during reboot test on a 3.0 based kernel but
the current code seems to be affected in the same way.

[jejb: additional comment added]
Reported-and-debugged-by: Mike Mayer <Mike.Meyer@teradata.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 drivers/scsi/scsi_error.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 066e3198838d..ff2689d01209 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -1906,8 +1906,17 @@ int scsi_error_handler(void *data)
 	 * We never actually get interrupted because kthread_run
 	 * disables signal delivery for the created thread.
 	 */
-	while (!kthread_should_stop()) {
+	while (true) {
+		/*
+		 * The sequence in kthread_stop() sets the stop flag first
+		 * then wakes the process.  To avoid missed wakeups, the task
+		 * should always be in a non running state before the stop
+		 * flag is checked
+		 */
 		set_current_state(TASK_INTERRUPTIBLE);
+		if (kthread_should_stop())
+			break;
+
 		if ((shost->host_failed == 0 && shost->host_eh_scheduled == 0) ||
 		    shost->host_failed != shost->host_busy) {
 			SCSI_LOG_ERROR_RECOVERY(1,
-- 
2.6.2

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Thread

[PATCH 3.12 001/123] x86/nmi/64: Fix a paravirt stack-clobbering bug in the NMI code Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:00 +0100
  [PATCH 3.12 027/123] ARM: dts: omap5-uevm.dts: fix i2c5 pinctrl offsets Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:00 +0100
  [PATCH 3.12 035/123] arc,hexagon: Delete asm/barrier.h Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:00 +0100
  [PATCH 3.12 037/123] spi: Fix documentation of spi_alloc_master() Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:00 +0100
  [PATCH 3.12 029/123] x86/apic: Serialize LVTT and TSC_DEADLINE writes Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:00 +0100
  [PATCH 3.12 026/123] windfarm: decrement client count when unregistering Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:00 +0100
  [PATCH 3.12 021/123] perf stat: Get correct cpu id for print_aggr Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:30 +0100
  [PATCH 3.12 030/123] x86/platform: Fix Geode LX timekeeping in the generic x86 build Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:30 +0100
  [PATCH 3.12 031/123] x86/mm: Set NX on gap between __ex_table and rodata Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:30 +0100
  [PATCH 3.12 033/123] arch: Clean up asm/barrier.h implementations using asm-generic/barrier.h Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:30 +0100
  [PATCH 3.12 032/123] x86/xen: Support kexec/kdump in HVM guests by doing a soft reset Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:30 +0100
    Re: [PATCH 3.12 032/123] x86/xen: Support kexec/kdump in HVM guests  by doing a soft reset Luis Henriques <luis.henriques@canonical.com> - 2015-10-28 16:30 +0100
      Re: [PATCH 3.12 032/123] x86/xen: Support kexec/kdump in HVM guests  by doing a soft reset Jiri Slaby <jslaby@suse.cz> - 2015-10-28 16:40 +0100
  [PATCH 3.12 022/123] perf header: Fixup reading of HEADER_NRCPUS feature Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:30 +0100
  [PATCH 3.12 034/123] arch: Move smp_mb__{before,after}_atomic_{inc,dec}.h into asm/atomic.h Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:30 +0100
  [PATCH 3.12 025/123] ARM: 8429/1: disable GCC SRA optimization Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:30 +0100
  [PATCH 3.12 028/123] dmaengine: dw: properly read DWC_PARAMS register Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:30 +0100
  [PATCH 3.12 014/123] ARM: 7880/1: Clear the IT state independent of the Thumb-2 mode Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:40 +0100
  [PATCH 3.12 036/123] sched/core: Fix TASK_DEAD race in finish_task_switch() Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:40 +0100
  [PATCH 3.12 012/123] s390/3270: redraw screen on unsolicited device end Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:40 +0100
  [PATCH 3.12 013/123] Use WARN_ON_ONCE for missing X86_FEATURE_NRIPS Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:40 +0100
  [PATCH 3.12 023/123] hwmon: (nct6775) Swap STEP_UP_TIME and STEP_DOWN_TIME registers for most chips Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:40 +0100
  [PATCH 3.12 017/123] kvm: fix zero length mmio searching Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:40 +0100
  [PATCH 3.12 018/123] scsi: fix scsi_error_handler vs. scsi_host_dev_release race Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:40 +0100
  [PATCH 3.12 002/123] x86/paravirt: Replace the paravirt nop with a bona fide empty function Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:40 +0100
  [PATCH 3.12 020/123] perf hists: Update the column width for the "srcline" sort key Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:40 +0100
  [PATCH 3.12 019/123] iser-target: remove command with state ISTATE_REMOVE Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:40 +0100
  [PATCH 3.12 024/123] ARM: fix Thumb2 signal handling when ARMv6 is enabled Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:40 +0100
  [PATCH 3.12 016/123] ALSA: hda - Control SPDIF out pin on MacBookPro 11,2 Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:40 +0100
  [PATCH 3.12 015/123] net: add length argument to skb_copy_and_csum_datagram_iovec Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:40 +0100
  [PATCH 3.12 004/123] rcu: Reject memory-order-induced stall-warning false positives Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:50 +0100
  [PATCH 3.12 005/123] sched: Fix cpu_active_mask/cpu_online_mask race Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:50 +0100
  [PATCH 3.12 007/123] xhci: rework cycle bit checking for new dequeue pointers Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:50 +0100
  [PATCH 3.12 006/123] xhci: Workaround for PME stuck issues in Intel xhci Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:50 +0100
  [PATCH 3.12 009/123] USB: usbtmc: add device quirk for Rigol DS6104 Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:50 +0100
    Re: [PATCH 3.12 009/123] USB: usbtmc: add device quirk for Rigol DS6104 Teunis van Beelen <teuniz@gmail.com> - 2015-10-28 16:40 +0100
  [PATCH 3.12 008/123] usb: core: Fix USB 3.0 devices lost in NOTATTACHED state after a hub port reset Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:50 +0100
  [PATCH 3.12 010/123] client MUST ignore EncryptionKeyLength if CAP_EXTENDED_SECURITY is set Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:50 +0100
  [PATCH 3.12 011/123] iommu/amd: Handle integer overflow in dma_ops_area_alloc Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:50 +0100
  [PATCH 3.12 003/123] jbd2: avoid infinite loop when destroying aborted journal Jiri Slaby <jslaby@suse.cz> - 2015-10-28 15:50 +0100

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