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net/tg3: resolve deadlock in tg3_reset_task() during EEH

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[ Upstream commit 6c4ca03bd890566d873e3593b32d034bf2f5a087 ]

During EEH error injection testing, a deadlock was encountered in the tg3
driver when tg3_io_error_detected() was attempting to cancel outstanding
reset tasks:

crash> foreach UN bt
...
PID: 159    TASK: c0000000067c6000  CPU: 8   COMMAND: "eehd"
...
 #5 [c00000000681f990] __cancel_work_timer at c00000000019fd18
 #6 [c00000000681fa30] tg3_io_error_detected at c00800000295f098 [tg3]
 #7 [c00000000681faf0] eeh_report_error at c00000000004e25c
...

PID: 290    TASK: c000000036e5f800  CPU: 6   COMMAND: "kworker/6:1"
...
 #4 [c00000003721fbc0] rtnl_lock at c000000000c940d8
 #5 [c00000003721fbe0] tg3_reset_task at c008000002969358 [tg3]
 #6 [c00000003721fc60] process_one_work at c00000000019e5c4
...

PID: 296    TASK: c000000037a65800  CPU: 21  COMMAND: "kworker/21:1"
...
 #4 [c000000037247bc0] rtnl_lock at c000000000c940d8
 #5 [c000000037247be0] tg3_reset_task at c008000002969358 [tg3]
 #6 [c000000037247c60] process_one_work at c00000000019e5c4
...

PID: 655    TASK: c000000036f49000  CPU: 16  COMMAND: "kworker/16:2"
...:1

 #4 [c0000000373ebbc0] rtnl_lock at c000000000c940d8
 #5 [c0000000373ebbe0] tg3_reset_task at c008000002969358 [tg3]
 #6 [c0000000373ebc60] process_one_work at c00000000019e5c4
...

Code inspection shows that both tg3_io_error_detected() and
tg3_reset_task() attempt to acquire the RTNL lock at the beginning of
their code blocks.  If tg3_reset_task() should happen to execute between
the times when tg3_io_error_deteced() acquires the RTNL lock and
tg3_reset_task_cancel() is called, a deadlock will occur.

Moving tg3_reset_task_cancel() call earlier within the code block, prior
to acquiring RTNL, prevents this from happening, but also exposes another
deadlock issue where tg3_reset_task() may execute AFTER
tg3_io_error_detected() has executed:

crash> foreach UN bt
PID: 159    TASK: c0000000067d2000  CPU: 9   COMMAND: "eehd"
...
 #4 [c000000006867a60] rtnl_lock at c000000000c940d8
 #5 [c000000006867a80] tg3_io_slot_reset at c0080000026c2ea8 [tg3]
 #6 [c000000006867b00] eeh_report_reset at c00000000004de88
...
PID: 363    TASK: c000000037564000  CPU: 6   COMMAND: "kworker/6:1"
...
 #3 [c000000036c1bb70] msleep at c000000000259e6c
 #4 [c000000036c1bba0] napi_disable at c000000000c6b848
 #5 [c000000036c1bbe0] tg3_reset_task at c0080000026d942c [tg3]
 #6 [c000000036c1bc60] process_one_work at c00000000019e5c4
...

This issue can be avoided by aborting tg3_reset_task() if EEH error
recovery is already in progress.

Fixes: db84bf43ef ("tg3: tg3_reset_task() needs to use rtnl_lock to synchronize")
Signed-off-by: David Christensen <drc@linux.vnet.ibm.com>
Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Link: https://lore.kernel.org/r/20230124185339.225806-1-drc@linux.vnet.ibm.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
David Christensen 2023-01-24 13:53:39 -05:00 committed by Greg Kroah-Hartman
parent 92a65b0f20
commit a9a022a0db
1 changed files with 4 additions and 4 deletions
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8
drivers/net/ethernet/broadcom/tg3.c
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@ -11195,7 +11195,7 @@ static void tg3_reset_task(struct work_struct *work)
rtnl_lock();
tg3_full_lock(tp, 0);
if (!netif_running(tp->dev)) {
if (tp->pcierr_recovery || !netif_running(tp->dev)) {
tg3_flag_clear(tp, RESET_TASK_PENDING);
tg3_full_unlock(tp);
rtnl_unlock();
@ -18187,6 +18187,9 @@ static pci_ers_result_t tg3_io_error_detected(struct pci_dev *pdev,
netdev_info(netdev, "PCI I/O error detected\n");
/* Want to make sure that the reset task doesn't run */
tg3_reset_task_cancel(tp);
rtnl_lock();
/* Could be second call or maybe we don't have netdev yet */
@ -18203,9 +18206,6 @@ static pci_ers_result_t tg3_io_error_detected(struct pci_dev *pdev,
tg3_timer_stop(tp);
/* Want to make sure that the reset task doesn't run */
tg3_reset_task_cancel(tp);
netif_device_detach(netdev);
/* Clean up software state, even if MMIO is blocked */