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Subject[PATCH v4 1/1] scsi: ufs: core: fix device management cmd timeout flow
Date
From: Mason Zhang <Mason.Zhang@mediatek.com>

In ufs error handler flow, host will send device management cmd(NOP OUT)
to device for recovery link. If cmd response timeout, and clear doorbell
fail, ufshcd_wait_for_dev_cmd will do nothing and return,
hba->dev_cmd.complete struct not set to null.

In this time, if cmd has been responsed by device, then it will
call complete() in __ufshcd_transfer_req_compl, because of complete
struct is alloced in stack, then the KE will occur.

Fix the following crash:
ipanic_die+0x24/0x38 [mrdump]
die+0x344/0x748
arm64_notify_die+0x44/0x104
do_debug_exception+0x104/0x1e0
el1_dbg+0x38/0x54
el1_sync_handler+0x40/0x88
el1_sync+0x8c/0x140
queued_spin_lock_slowpath+0x2e4/0x3c0
__ufshcd_transfer_req_compl+0x3b0/0x1164
ufshcd_trc_handler+0x15c/0x308
ufshcd_host_reset_and_restore+0x54/0x260
ufshcd_reset_and_restore+0x28c/0x57c
ufshcd_err_handler+0xeb8/0x1b6c
process_one_work+0x288/0x964
worker_thread+0x4bc/0xc7c
kthread+0x15c/0x264
ret_from_fork+0x10/0x30

Signed-off-by: Mason Zhang <Mason.Zhang@mediatek.com>
---
Changes since v3:
* Not clear outstanding_reqs if clear cmds fail.
Updated the patch in v4.
Changes since v2:
* Modified comment after clear doorbell.
Changes since v1:
* Remove change id.
---
drivers/ufs/core/ufshcd.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index b1f59a5fe632..fa86ce80f350 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -3008,6 +3008,22 @@ static int ufshcd_wait_for_dev_cmd(struct ufs_hba *hba,
} else {
dev_err(hba->dev, "%s: failed to clear tag %d\n",
__func__, lrbp->task_tag);
+
+ spin_lock_irqsave(&hba->outstanding_lock, flags);
+ pending = test_bit(lrbp->task_tag,
+ &hba->outstanding_reqs);
+ if (pending)
+ hba->dev_cmd.complete = NULL;
+ spin_unlock_irqrestore(&hba->outstanding_lock, flags);
+
+ if (!pending) {
+ /*
+ * The completion handler ran while we tried to
+ * clear the command.
+ */
+ time_left = 1;
+ goto retry;
+ }
}
}

--
2.18.0
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