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[PATCH v8 03/17] scsi: ufs: implement scsi host timeout handler

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A race condition exists between request requeueing and scsi layer
error handling:
When UFS driver queuecommand returns a busy status for a request,
it will be requeued and its tag will be freed and set to -1.
At the same time it is possible that the request will timeout and
scsi layer will start error handling for it. The scsi layer reuses
the request and its tag to send error related commands to the device,
however its tag is no longer valid.
As this request was never really sent to the device, there is no
point to start error handling with the device.
Implement the scsi error handling timeout callback and bypass SCSI
error handling for request that were not actually sent to the device.
For such requests simply reset the block layer timer. Otherwise, let
SCSI layer perform the usual error handling.

Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Gilad Broner <gbroner@codeaurora.org>
Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>

---
 drivers/scsi/ufs/ufshcd.c | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index de7280c..3400ceb 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -4568,6 +4568,41 @@ static void ufshcd_async_scan(void *data, async_cookie_t cookie)
 	ufshcd_probe_hba(hba);
 }
 
+static enum blk_eh_timer_return ufshcd_eh_timed_out(struct scsi_cmnd *scmd)
+{
+	unsigned long flags;
+	struct Scsi_Host *host;
+	struct ufs_hba *hba;
+	int index;
+	bool found = false;
+
+	if (!scmd || !scmd->device || !scmd->device->host)
+		return BLK_EH_NOT_HANDLED;
+
+	host = scmd->device->host;
+	hba = shost_priv(host);
+	if (!hba)
+		return BLK_EH_NOT_HANDLED;
+
+	spin_lock_irqsave(host->host_lock, flags);
+
+	for_each_set_bit(index, &hba->outstanding_reqs, hba->nutrs) {
+		if (hba->lrb[index].cmd == scmd) {
+			found = true;
+			break;
+		}
+	}
+
+	spin_unlock_irqrestore(host->host_lock, flags);
+
+	/*
+	 * Bypass SCSI error handling and reset the block layer timer if this
+	 * SCSI command was not actually dispatched to UFS driver, otherwise
+	 * let SCSI layer handle the error as usual.
+	 */
+	return found ? BLK_EH_NOT_HANDLED : BLK_EH_RESET_TIMER;
+}
+
 static struct scsi_host_template ufshcd_driver_template = {
 	.module			= THIS_MODULE,
 	.name			= UFSHCD,
@@ -4580,6 +4615,7 @@ static struct scsi_host_template ufshcd_driver_template = {
 	.eh_abort_handler	= ufshcd_abort,
 	.eh_device_reset_handler = ufshcd_eh_device_reset_handler,
 	.eh_host_reset_handler   = ufshcd_eh_host_reset_handler,
+	.eh_timed_out		= ufshcd_eh_timed_out,
 	.this_id		= -1,
 	.sg_tablesize		= SG_ALL,
 	.cmd_per_lun		= UFSHCD_CMD_PER_LUN,
-- 
1.8.5.2

-- 
QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

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Thread

[PATCH v8 00/17] add fixes, device quirks, error recovery, Yaniv Gardi <ygardi@codeaurora.org> - 2016-03-10 16:40 +0100
  [PATCH v8 02/17] scsi: ufs: avoid spurious UFS host controller interrupts Yaniv Gardi <ygardi@codeaurora.org> - 2016-03-10 16:40 +0100
  [PATCH v8 17/17] scsi: ufs-qcom: add printouts of testbus debug registers Yaniv Gardi <ygardi@codeaurora.org> - 2016-03-10 16:40 +0100
  [PATCH v8 01/17] scsi: ufs-qcom: add number of lanes per direction Yaniv Gardi <ygardi@codeaurora.org> - 2016-03-10 16:40 +0100
  [PATCH v8 10/17] scsi: ufs: add retry for query descriptors Yaniv Gardi <ygardi@codeaurora.org> - 2016-03-10 16:40 +0100
  [PATCH v8 13/17] scsi: ufs: fix leakage during link off state Yaniv Gardi <ygardi@codeaurora.org> - 2016-03-10 16:40 +0100
  [PATCH v8 16/17] scsi: ufs-qcom: enable/disable the device ref clock Yaniv Gardi <ygardi@codeaurora.org> - 2016-03-10 16:40 +0100
  [PATCH v8 11/17] scsi: ufs: handle non spec compliant bkops behaviour by device Yaniv Gardi <ygardi@codeaurora.org> - 2016-03-10 16:40 +0100
  [PATCH v8 04/17] scsi: ufs: verify hba controller hce reg value Yaniv Gardi <ygardi@codeaurora.org> - 2016-03-10 16:40 +0100
  [PATCH v8 15/17] scsi: ufs-qcom: set PA_Local_TX_LCC_Enable before link startup Yaniv Gardi <ygardi@codeaurora.org> - 2016-03-10 16:40 +0100
  [PATCH v8 08/17] scsi: ufs: make error handling bit faster Yaniv Gardi <ygardi@codeaurora.org> - 2016-03-10 16:50 +0100
  [PATCH v8 14/17] scsi: ufs: add device quirk delay before putting UFS rails in LPM Yaniv Gardi <ygardi@codeaurora.org> - 2016-03-10 16:50 +0100
  [PATCH v8 07/17] scsi: ufs: disable vccq if it's not needed by UFS device Yaniv Gardi <ygardi@codeaurora.org> - 2016-03-10 16:50 +0100
  [PATCH v8 05/17] scsi: ufs: add support to read device and string descriptors Yaniv Gardi <ygardi@codeaurora.org> - 2016-03-10 16:50 +0100
  [PATCH v8 09/17] scsi: ufs: add error recovery after DL NAC error Yaniv Gardi <ygardi@codeaurora.org> - 2016-03-10 16:50 +0100
  [PATCH v8 06/17] scsi: ufs: separate device and host quirks Yaniv Gardi <ygardi@codeaurora.org> - 2016-03-10 16:50 +0100
  [PATCH v8 03/17] scsi: ufs: implement scsi host timeout handler Yaniv Gardi <ygardi@codeaurora.org> - 2016-03-10 16:50 +0100
  [PATCH v8 12/17] scsi: ufs: tune UniPro parameters to optimize hibern8 exit time Yaniv Gardi <ygardi@codeaurora.org> - 2016-03-10 16:50 +0100
  Re: [PATCH v8 00/17] add fixes, device quirks, error recovery, "Martin K. Petersen" <martin.petersen@oracle.com> - 2016-03-11 03:40 +0100
    Re: [PATCH v8 00/17] add fixes, device quirks, error recovery, Hannes Reinecke <hare@suse.de> - 2016-03-11 10:00 +0100
  Re: [PATCH v8 00/17] add fixes, device quirks, error recovery, "Martin K. Petersen" <martin.petersen@oracle.com> - 2016-03-14 21:10 +0100

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