[3.13.y-ckt stable] Patch "3w-xxxx: fix command completion race" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    3w-xxxx: fix command completion race

to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11-ckt22.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From c37f294d7e77ee9f34976e18e6420afa59cfd7d2 Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch at lst.de>
Date: Thu, 23 Apr 2015 09:48:50 +0200
Subject: 3w-xxxx: fix command completion race

commit 9cd9554615cba14f0877cc9972a6537ad2bdde61 upstream.

The 3w-xxxx driver needs to tear down the dma mappings before returning
the command to the midlayer, as there is no guarantee the sglist and
count are valid after that point.  Also remove the dma mapping helpers
which have another inherent race due to the request_id index.

Signed-off-by: Christoph Hellwig <hch at lst.de>
Acked-by: Adam Radford <aradford at gmail.com>
Signed-off-by: James Bottomley <JBottomley at Odin.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/scsi/3w-xxxx.c | 42 ++++++------------------------------------
 drivers/scsi/3w-xxxx.h |  5 -----
 2 files changed, 6 insertions(+), 41 deletions(-)

diff --git a/drivers/scsi/3w-xxxx.c b/drivers/scsi/3w-xxxx.c
index 752624e..b327742 100644
--- a/drivers/scsi/3w-xxxx.c
+++ b/drivers/scsi/3w-xxxx.c
@@ -1284,32 +1284,6 @@ static int tw_initialize_device_extension(TW_Device_Extension *tw_dev)
 	return 0;
 } /* End tw_initialize_device_extension() */

-static int tw_map_scsi_sg_data(struct pci_dev *pdev, struct scsi_cmnd *cmd)
-{
-	int use_sg;
-
-	dprintk(KERN_WARNING "3w-xxxx: tw_map_scsi_sg_data()\n");
-
-	use_sg = scsi_dma_map(cmd);
-	if (use_sg < 0) {
-		printk(KERN_WARNING "3w-xxxx: tw_map_scsi_sg_data(): pci_map_sg() failed.\n");
-		return 0;
-	}
-
-	cmd->SCp.phase = TW_PHASE_SGLIST;
-	cmd->SCp.have_data_in = use_sg;
-
-	return use_sg;
-} /* End tw_map_scsi_sg_data() */
-
-static void tw_unmap_scsi_data(struct pci_dev *pdev, struct scsi_cmnd *cmd)
-{
-	dprintk(KERN_WARNING "3w-xxxx: tw_unmap_scsi_data()\n");
-
-	if (cmd->SCp.phase == TW_PHASE_SGLIST)
-		scsi_dma_unmap(cmd);
-} /* End tw_unmap_scsi_data() */
-
 /* This function will reset a device extension */
 static int tw_reset_device_extension(TW_Device_Extension *tw_dev)
 {
@@ -1332,8 +1306,8 @@ static int tw_reset_device_extension(TW_Device_Extension *tw_dev)
 			srb = tw_dev->srb[i];
 			if (srb != NULL) {
 				srb->result = (DID_RESET << 16);
-				tw_dev->srb[i]->scsi_done(tw_dev->srb[i]);
-				tw_unmap_scsi_data(tw_dev->tw_pci_dev, tw_dev->srb[i]);
+				scsi_dma_unmap(srb);
+				srb->scsi_done(srb);
 			}
 		}
 	}
@@ -1780,8 +1754,8 @@ static int tw_scsiop_read_write(TW_Device_Extension *tw_dev, int request_id)
 	command_packet->byte8.io.lba = lba;
 	command_packet->byte6.block_count = num_sectors;

-	use_sg = tw_map_scsi_sg_data(tw_dev->tw_pci_dev, tw_dev->srb[request_id]);
-	if (!use_sg)
+	use_sg = scsi_dma_map(srb);
+	if (use_sg <= 0)
 		return 1;

 	scsi_for_each_sg(tw_dev->srb[request_id], sg, use_sg, i) {
@@ -1968,9 +1942,6 @@ static int tw_scsi_queue_lck(struct scsi_cmnd *SCpnt, void (*done)(struct scsi_c
 	/* Save the scsi command for use by the ISR */
 	tw_dev->srb[request_id] = SCpnt;

-	/* Initialize phase to zero */
-	SCpnt->SCp.phase = TW_PHASE_INITIAL;
-
 	switch (*command) {
 		case READ_10:
 		case READ_6:
@@ -2198,12 +2169,11 @@ static irqreturn_t tw_interrupt(int irq, void *dev_instance)

 				/* Now complete the io */
 				if ((error != TW_ISR_DONT_COMPLETE)) {
+					scsi_dma_unmap(tw_dev->srb[request_id]);
+					tw_dev->srb[request_id]->scsi_done(tw_dev->srb[request_id]);
 					tw_dev->state[request_id] = TW_S_COMPLETED;
 					tw_state_request_finish(tw_dev, request_id);
 					tw_dev->posted_request_count--;
-					tw_dev->srb[request_id]->scsi_done(tw_dev->srb[request_id]);
-
-					tw_unmap_scsi_data(tw_dev->tw_pci_dev, tw_dev->srb[request_id]);
 				}
 			}

diff --git a/drivers/scsi/3w-xxxx.h b/drivers/scsi/3w-xxxx.h
index 49dcf03..1d31858 100644
--- a/drivers/scsi/3w-xxxx.h
+++ b/drivers/scsi/3w-xxxx.h
@@ -195,11 +195,6 @@ static unsigned char tw_sense_table[][4] =
 #define TW_AEN_SMART_FAIL        0x000F
 #define TW_AEN_SBUF_FAIL         0x0024

-/* Phase defines */
-#define TW_PHASE_INITIAL 0
-#define TW_PHASE_SINGLE 1
-#define TW_PHASE_SGLIST 2
-
 /* Misc defines */
 #define TW_ALIGNMENT_6000		      64 /* 64 bytes */
 #define TW_ALIGNMENT_7000                     4  /* 4 bytes */
--
1.9.1