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qla2xxx: fix a timeout loop

PATCH Applied Dan Carpenter 4 participants 6 messages Dec 16, 2015 – Dec 17, 2015

Subsystems (3)
SCSI Kernel janitors QLogic QLA2XXX FC-SCSI driver
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Dan Carpenter

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#0 lore raw

PATCH 1/1 qla2xxx: fix a timeout loop

After the loop we test for "if (!retries) " as a failure, but actually the post-op here will end with retries set to -1. I have fixed this by using a pre-op instead.

Fixes 7ec0effd30bb ('[SCSI] qla2xxx: Add support for ISP8044.')
Signed-off-by Dan Carpenter <[email protected]>
drivers/scsi/qla2xxx/qla_nx2.c +1 -1
index 007192d..66d629e 100644
@@ -3491,7 +3491,7 @@ qla8044_poll_flash_status_reg(struct scsi_qla_host *vha)
 	int retries = QLA8044_FLASH_READ_RETRY_COUNT;
 	int ret_val = QLA_SUCCESS;
 
-	while (retries--) {
+	while (--retries) {
 		ret_val = qla8044_rd_reg_indirect(vha, QLA8044_FLASH_STATUS,
 		    &flash_status);
 		if (ret_val) {
Reviewed-by on v1 1/1
#1 lore raw
Quoted 21 lines · Dan Carpenter

After the loop we test for "if (!retries) " as a failure, but actually the post-op here will end with retries set to -1. I have fixed this by using a pre-op instead.

Fixes 7ec0effd30bb ('[SCSI] qla2xxx: Add support for ISP8044.')
Signed-off-by Dan Carpenter <[email protected]>
drivers/scsi/qla2xxx/qla_nx2.c +1 -2
index 007192d..66d629e 100644
@@ -3491,7 +3491,7 @@ qla8044_poll_flash_status_reg(struct scsi_qla_host *vha)
 	int retries = QLA8044_FLASH_READ_RETRY_COUNT;
 	int ret_val = QLA_SUCCESS;
 
-	while (retries--) {
+	while (--retries) {
 		ret_val = qla8044_rd_reg_indirect(vha, QLA8044_FLASH_STATUS,
 		    &flash_status);
 		if (ret_val) {
--
Quoted 3 lines

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Good catch.

Reviewed-by Johannes Thumshirn <[email protected]>
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Johannes Thumshirn                                          Storage
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SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
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Applied
#2 lore raw
In reply to Dan Carpenter
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"Dan" = Dan Carpenter <[email protected]> writes:

Dan> After the loop we test for "if (!retries) " as a failure, but Dan> actually the post-op here will end with retries set to -1. I have Dan> fixed this by using a pre-op instead.

Applied to 4.4/scsi-fixes.

Signature · 1 line
Martin K. Petersen	Oracle Linux Engineering
author
#3 lore raw
Quoted 8 lines · Martin K. Petersen
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"Dan" = Dan Carpenter <[email protected]> writes:

Dan> After the loop we test for "if (!retries) " as a failure, but Dan> actually the post-op here will end with retries set to -1. I have Dan> fixed this by using a pre-op instead.

Applied to 4.4/scsi-fixes.

The qlogic devs asked me to redo this patch but you have already applied it. Should I resend or redo it on top of the earlier patch. (James's tree was rebaseable for a day after a patch was "applied".)

regards,
dan carpenter

#4 lore raw
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"Dan" = Dan Carpenter <[email protected]> writes:

Dan> The qlogic devs asked me to redo this patch but you have already Dan> applied it. Should I resend or redo it on top of the earlier Dan> patch. (James's tree was rebaseable for a day after a patch was Dan> "applied".)

I dropped it for now.

Signature · 1 line
Martin K. Petersen	Oracle Linux Engineering
#5 lore raw
In reply to Dan Carpenter

Hi Dan,

Quoted 21 lines · On 12/16/15, 3:07 AM, "[email protected] on behalf of Dan…

After the loop we test for "if (!retries) " as a failure, but actually the post-op here will end with retries set to -1. I have fixed this by using a pre-op instead.

Fixes 7ec0effd30bb ('[SCSI] qla2xxx: Add support for ISP8044.')
Signed-off-by Dan Carpenter <[email protected]>
drivers/scsi/qla2xxx/qla_nx2.c +1 -1
index 007192d..66d629e 100644
@@ -3491,7 +3491,7 @@ qla8044_poll_flash_status_reg(struct scsi_qla_host
 *vha)
 	int retries = QLA8044_FLASH_READ_RETRY_COUNT;
 	int ret_val = QLA_SUCCESS;
 
-	while (retries--) {
+	while (--retries) {
 		ret_val = qla8044_rd_reg_indirect(vha, QLA8044_FLASH_STATUS,
 		    &flash_status);
Quoted 1 line
		if (ret_val) {

There is flaw in this pre-decrement logic here for following 2 reasons
1. The pre-decrement reduces the total number of retries by one
2. If the retries is already Zero, then the pre-decrement would cause loop to iterate for a very large number of times.

The correct fix for this would be to change the if(!retries) to if (retries = -1) or if (retries < 0)

We¹ll send a follow up patch to fix this.

Thanks,
Himanshu

Quoted 4 lines

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