[PATCH 8/8] scsi: ufs: Check for completion from the timeout handler

[Bart Van Assche <bvanassche@acm.org>]

If ufshcd_abort() returns SUCCESS for an already completed command then
that command is completed twice. This results in a crash. Prevent this by
checking whether a command has completed without completion interrupt from
the timeout handler. This CL fixes the following kernel crash:

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
Call trace:
 dma_direct_map_sg+0x70/0x274
 scsi_dma_map+0x84/0x124
 ufshcd_queuecommand+0x3fc/0x880
 scsi_queue_rq+0x7d0/0x111c
 blk_mq_dispatch_rq_list+0x440/0xebc
 blk_mq_do_dispatch_sched+0x5a4/0x6b8
 __blk_mq_sched_dispatch_requests+0x150/0x220
 __blk_mq_run_hw_queue+0xf0/0x218
 __blk_mq_delay_run_hw_queue+0x8c/0x18c
 blk_mq_run_hw_queue+0x1a4/0x360
 blk_mq_sched_insert_requests+0x130/0x334
 blk_mq_flush_plug_list+0x138/0x234
 blk_flush_plug_list+0x118/0x164
 blk_finish_plug()
 read_pages+0x38c/0x408
 page_cache_ra_unbounded+0x230/0x2f8
 do_sync_mmap_readahead+0x1a4/0x208
 filemap_fault+0x27c/0x8f4
 f2fs_filemap_fault+0x28/0xfc
 __do_fault+0xc4/0x208
 handle_pte_fault+0x290/0xe04
 do_handle_mm_fault+0x52c/0x858
 do_page_fault+0x5dc/0x798
 do_translation_fault+0x40/0x54
 do_mem_abort+0x60/0x134
 el0_da+0x40/0xb8
 el0t_64_sync_handler+0xc4/0xe4
 el0t_64_sync+0x1b4/0x1b8

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/ufs/core/ufshcd.c | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index e3835e61e4b1..47cc0802c4f4 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -8922,7 +8922,28 @@ static void ufshcd_async_scan(void *data, async_cookie_t cookie)
 
 static enum scsi_timeout_action ufshcd_eh_timed_out(struct scsi_cmnd *scmd)
 {
-	struct ufs_hba *hba = shost_priv(scmd->device->host);
+	struct scsi_device *sdev = scmd->device;
+	struct ufs_hba *hba = shost_priv(sdev->host);
+	struct scsi_cmnd *cmd2 = scmd;
+	const u32 unique_tag = blk_mq_unique_tag(scsi_cmd_to_rq(scmd));
+
+	WARN_ON_ONCE(!scmd);
+
+	if (is_mcq_enabled(hba)) {
+		struct request *rq = scsi_cmd_to_rq(scmd);
+		struct ufs_hw_queue *hwq = ufshcd_mcq_req_to_hwq(hba, rq);
+
+		ufshcd_mcq_poll_cqe_lock(hba, hwq, &cmd2);
+	} else {
+		__ufshcd_poll(hba->host, UFSHCD_POLL_FROM_INTERRUPT_CONTEXT,
+			      &cmd2);
+	}
+	if (cmd2 == NULL) {
+		sdev_printk(KERN_INFO, sdev,
+			    "%s: cmd with tag %#x has already been completed\n",
+			    __func__, unique_tag);
+		return SCSI_EH_DONE;
+	}
 
 	if (!hba->system_suspending) {
 		/* Activate the error handler in the SCSI core. */