[PATCH 3.2 161/164] [SCSI] hpsa: fix a race in cmd_free/scsi_done

[Ben Hutchings]

3.2.65-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Tomas Henzl <thenzl@xxxxxxxxxx>

commit 2cc5bfaf854463d9d1aa52091f60110fbf102a96 upstream.

When the driver calls scsi_done and after that frees it's internal
preallocated memory it can happen that a new job is enqueud before
the memory is freed. The allocation fails and the message
"cmd_alloc returned NULL" is shown.
Patch below fixes it by moving cmd->scsi_done after cmd_free.

Signed-off-by: Tomas Henzl <thenzl@xxxxxxxxxx>
Acked-by: Stephen M. Cameron <scameron@xxxxxxxxxxxxxxxxxx>
Signed-off-by: James Bottomley <JBottomley@xxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Cc: Masoud Sharbiani <msharbiani@xxxxxxxxxxxxxxxx>
---
 drivers/scsi/hpsa.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/scsi/hpsa.c
+++ b/drivers/scsi/hpsa.c
@@ -1126,8 +1126,8 @@ static void complete_scsi_command(struct
 	scsi_set_resid(cmd, ei->ResidualCnt);
 
 	if (ei->CommandStatus == 0) {
-		cmd->scsi_done(cmd);
 		cmd_free(h, cp);
+		cmd->scsi_done(cmd);
 		return;
 	}
 
@@ -1300,8 +1300,8 @@ static void complete_scsi_command(struct
 		dev_warn(&h->pdev->dev, "cp %p returned unknown status %x\n",
 				cp, ei->CommandStatus);
 	}
-	cmd->scsi_done(cmd);
 	cmd_free(h, cp);
+	cmd->scsi_done(cmd);
 }
 
 static int hpsa_scsi_detect(struct ctlr_info *h)

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