Updated to address comments from Jens and Bart.
Accounting for the first change (below) introduces modifications to a
bunch of files. If this patch should be formatted differently or copied
to additional people / lists, let me know. The patch is based on the
for-next branch from Jens' linux-block tree.
Changes from v1:
- Distinguish error conditions in __get_request using ERR_PTR instead
of NULL. (blk_queue_dying will return ERR_PTR(-ENODEV), but should
the other error paths all return ERR_PTR(-ENOMEM) ?)
- Propagate ERR_PTR out from __get_request through blk_get_request,
updating callers accordingly.
Thanks,
-- Joe
>From 7122dd3ba8c3b1e7edff42ff9c21247fcf4379c2 Mon Sep 17 00:00:00 2001
From: Joe Lawrence <joe.lawrence@xxxxxxxxxxx>
Date: Tue, 26 Mar 2013 14:30:28 -0400
Subject: [PATCH v2] block: handle pointer error from blk_get_request
The blk_get_request function may fail in low-memory conditions or during
device removal (even if __GFP_WAIT is set). To distinguish between these
errors, modify the blk_get_request call stack to return the appropriate
error pointer. Verify that all callers check the return status and
consider IS_ERR instead of a simple NULL pointer check.
Signed-off-by: Joe Lawrence <joe.lawrence@xxxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: "James E.J. Bottomley" <JBottomley@xxxxxxxxxxxxx>
Cc: Bart Van Assche <bvanassche@xxxxxxx>
Cc: linux-scsi@xxxxxxxxxxxxxxx
---
block/blk-core.c | 30 ++++++++++++++---------------
block/bsg.c | 8 ++++----
block/scsi_ioctl.c | 8 ++++++--
drivers/block/paride/pd.c | 2 ++
drivers/block/pktcdvd.c | 3 ++-
drivers/block/sx8.c | 2 +-
drivers/cdrom/cdrom.c | 4 ++--
drivers/ide/ide-park.c | 2 +-
drivers/scsi/device_handler/scsi_dh_alua.c | 2 +-
drivers/scsi/device_handler/scsi_dh_emc.c | 2 +-
drivers/scsi/device_handler/scsi_dh_hp_sw.c | 4 ++--
drivers/scsi/device_handler/scsi_dh_rdac.c | 2 +-
drivers/scsi/osd/osd_initiator.c | 4 ++--
drivers/scsi/osst.c | 2 +-
drivers/scsi/scsi_error.c | 2 ++
drivers/scsi/scsi_lib.c | 2 +-
drivers/scsi/scsi_tgt_lib.c | 2 +-
drivers/scsi/sg.c | 4 ++--
drivers/scsi/st.c | 2 +-
drivers/target/target_core_pscsi.c | 4 ++--
20 files changed, 50 insertions(+), 41 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index f224d17..f6789b7 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -886,9 +886,9 @@ static struct io_context *rq_ioc(struct bio *bio)
* Get a free request from @q. This function may fail under memory
* pressure or if @q is dead.
*
- * Must be callled with @q->queue_lock held and,
- * Returns %NULL on failure, with @q->queue_lock held.
- * Returns !%NULL on success, with @q->queue_lock *not held*.
+ * Must be called with @q->queue_lock held and,
+ * Returns ERR_PTR on failure, with @q->queue_lock held.
+ * Returns request pointer on success, with @q->queue_lock *not held*.
*/
static struct request *__get_request(struct request_list *rl, int rw_flags,
struct bio *bio, gfp_t gfp_mask)
@@ -902,7 +902,7 @@ static struct request *__get_request(struct request_list *rl, int rw_flags,
int may_queue;
if (unlikely(blk_queue_dying(q)))
- return NULL;
+ return ERR_PTR(-ENODEV);
may_queue = elv_may_queue(q, rw_flags);
if (may_queue == ELV_MQUEUE_NO)
@@ -927,7 +927,7 @@ static struct request *__get_request(struct request_list *rl, int rw_flags,
* process is not a "batcher", and not
* exempted by the IO scheduler
*/
- return NULL;
+ return ERR_PTR(-ENOMEM);
}
}
}
@@ -945,7 +945,7 @@ static struct request *__get_request(struct request_list *rl, int rw_flags,
* allocated with any setting of ->nr_requests
*/
if (rl->count[is_sync] >= (3 * q->nr_requests / 2))
- return NULL;
+ return ERR_PTR(-ENOMEM);
q->nr_rqs[is_sync]++;
rl->count[is_sync]++;
@@ -1050,7 +1050,7 @@ fail_alloc:
rq_starved:
if (unlikely(rl->count[is_sync] == 0))
rl->starved[is_sync] = 1;
- return NULL;
+ return ERR_PTR(-ENOMEM);
}
/**
@@ -1063,9 +1063,9 @@ rq_starved:
* Get a free request from @q. If %__GFP_WAIT is set in @gfp_mask, this
* function keeps retrying under memory pressure and fails iff @q is dead.
*
- * Must be callled with @q->queue_lock held and,
- * Returns %NULL on failure, with @q->queue_lock held.
- * Returns !%NULL on success, with @q->queue_lock *not held*.
+ * Must be called with @q->queue_lock held and,
+ * Returns ERR_PTR on failure, with @q->queue_lock held.
+ * Returns request pointer on success, with @q->queue_lock *not held*.
*/
static struct request *get_request(struct request_queue *q, int rw_flags,
struct bio *bio, gfp_t gfp_mask)
@@ -1078,12 +1078,12 @@ static struct request *get_request(struct request_queue *q, int rw_flags,
rl = blk_get_rl(q, bio); /* transferred to @rq on success */
retry:
rq = __get_request(rl, rw_flags, bio, gfp_mask);
- if (rq)
+ if (!IS_ERR(rq))
return rq;
if (!(gfp_mask & __GFP_WAIT) || unlikely(blk_queue_dying(q))) {
blk_put_rl(rl);
- return NULL;
+ return rq;
}
/* wait on @rl and retry */
@@ -1119,7 +1119,7 @@ struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask)
spin_lock_irq(q->queue_lock);
rq = get_request(q, rw, NULL, gfp_mask);
- if (!rq)
+ if (unlikely(IS_ERR(rq)))
spin_unlock_irq(q->queue_lock);
/* q->queue_lock is unlocked at this point */
@@ -1528,8 +1528,8 @@ get_rq:
* Returns with the queue unlocked.
*/
req = get_request(q, rw_flags, bio, GFP_NOIO);
- if (unlikely(!req)) {
- bio_endio(bio, -ENODEV); /* @q is dead */
+ if (unlikely(IS_ERR(req))) {
+ bio_endio(bio, PTR_ERR(req)); /* @q is dead */
goto out_unlock;
}
diff --git a/block/bsg.c b/block/bsg.c
index 420a5a9..2b1c322 100644
--- a/block/bsg.c
+++ b/block/bsg.c
@@ -271,8 +271,8 @@ bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr, fmode_t has_write_perm,
* map scatter-gather elements separately and string them to request
*/
rq = blk_get_request(q, rw, GFP_KERNEL);
- if (!rq)
- return ERR_PTR(-ENOMEM);
+ if (IS_ERR(rq))
+ return rq;
ret = blk_fill_sgv4_hdr_rq(q, rq, hdr, bd, has_write_perm);
if (ret)
goto out;
@@ -284,8 +284,8 @@ bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr, fmode_t has_write_perm,
}
next_rq = blk_get_request(q, READ, GFP_KERNEL);
- if (!next_rq) {
- ret = -ENOMEM;
+ if (IS_ERR(next_rq)) {
+ ret = PTR_ERR(rq);
goto out;
}
rq->next_rq = next_rq;
diff --git a/block/scsi_ioctl.c b/block/scsi_ioctl.c
index 9a87daa..014b92a 100644
--- a/block/scsi_ioctl.c
+++ b/block/scsi_ioctl.c
@@ -311,8 +311,8 @@ static int sg_io(struct request_queue *q, struct gendisk *bd_disk,
}
rq = blk_get_request(q, writing ? WRITE : READ, GFP_KERNEL);
- if (!rq)
- return -ENOMEM;
+ if (IS_ERR(rq))
+ return PTR_ERR(rq);
if (blk_fill_sghdr_rq(q, rq, hdr, mode)) {
blk_put_request(rq);
@@ -458,6 +458,8 @@ int sg_scsi_ioctl(struct request_queue *q, struct gendisk *disk, fmode_t mode,
}
rq = blk_get_request(q, in_len ? WRITE : READ, __GFP_WAIT);
+ if (IS_ERR(rq))
+ return PTR_ERR(rq);
cmdlen = COMMAND_SIZE(opcode);
@@ -544,6 +546,8 @@ static int __blk_send_generic(struct request_queue *q, struct gendisk *bd_disk,
int err;
rq = blk_get_request(q, WRITE, __GFP_WAIT);
+ if (IS_ERR(rq))
+ return PTR_ERR(rq);
rq->cmd_type = REQ_TYPE_BLOCK_PC;
rq->timeout = BLK_DEFAULT_SG_TIMEOUT;
rq->cmd[0] = cmd;
diff --git a/drivers/block/paride/pd.c b/drivers/block/paride/pd.c
index 831e3ac..0d4e530 100644
--- a/drivers/block/paride/pd.c
+++ b/drivers/block/paride/pd.c
@@ -722,6 +722,8 @@ static int pd_special_command(struct pd_unit *disk,
int err = 0;
rq = blk_get_request(disk->gd->queue, READ, __GFP_WAIT);
+ if (IS_ERR(rq))
+ return PTR_ERR(rq);
rq->cmd_type = REQ_TYPE_SPECIAL;
rq->special = func;
diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
index 1119042..25ab3bd 100644
--- a/drivers/block/pktcdvd.c
+++ b/drivers/block/pktcdvd.c
@@ -711,7 +711,8 @@ static int pkt_generic_packet(struct pktcdvd_device *pd, struct packet_command *
rq = blk_get_request(q, (cgc->data_direction == CGC_DATA_WRITE) ?
WRITE : READ, __GFP_WAIT);
-
+ if (IS_ERR(rq))
+ return PTR_ERR(rq);
if (cgc->buflen) {
if (blk_rq_map_kern(q, rq, cgc->buffer, cgc->buflen, __GFP_WAIT))
goto out;
diff --git a/drivers/block/sx8.c b/drivers/block/sx8.c
index 3fb6ab4..911b7fc 100644
--- a/drivers/block/sx8.c
+++ b/drivers/block/sx8.c
@@ -568,7 +568,7 @@ static struct carm_request *carm_get_special(struct carm_host *host)
return NULL;
rq = blk_get_request(host->oob_q, WRITE /* bogus */, GFP_KERNEL);
- if (!rq) {
+ if (IS_ERR(rq)) {
spin_lock_irqsave(&host->lock, flags);
carm_put_request(host, crq);
spin_unlock_irqrestore(&host->lock, flags);
diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c
index d620b44..999d852 100644
--- a/drivers/cdrom/cdrom.c
+++ b/drivers/cdrom/cdrom.c
@@ -2161,8 +2161,8 @@ static int cdrom_read_cdda_bpc(struct cdrom_device_info *cdi, __u8 __user *ubuf,
len = nr * CD_FRAMESIZE_RAW;
rq = blk_get_request(q, READ, GFP_KERNEL);
- if (!rq) {
- ret = -ENOMEM;
+ if (IS_ERR(rq)) {
+ ret = PTR_ERR(rq);
break;
}
diff --git a/drivers/ide/ide-park.c b/drivers/ide/ide-park.c
index 6ab9ab2..fd432de 100644
--- a/drivers/ide/ide-park.c
+++ b/drivers/ide/ide-park.c
@@ -46,7 +46,7 @@ static void issue_park_cmd(ide_drive_t *drive, unsigned long timeout)
* timeout has expired, so power management will be reenabled.
*/
rq = blk_get_request(q, READ, GFP_NOWAIT);
- if (unlikely(!rq))
+ if (unlikely(IS_ERR(rq)))
goto out;
rq->cmd[0] = REQ_UNPARK_HEADS;
diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
index 6f4d8e6..f07f152 100644
--- a/drivers/scsi/device_handler/scsi_dh_alua.c
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -115,7 +115,7 @@ static struct request *get_alua_req(struct scsi_device *sdev,
rq = blk_get_request(q, rw, GFP_NOIO);
- if (!rq) {
+ if (IS_ERR(rq)) {
sdev_printk(KERN_INFO, sdev,
"%s: blk_get_request failed\n", __func__);
return NULL;
diff --git a/drivers/scsi/device_handler/scsi_dh_emc.c b/drivers/scsi/device_handler/scsi_dh_emc.c
index e1c8be0..2ec3261 100644
--- a/drivers/scsi/device_handler/scsi_dh_emc.c
+++ b/drivers/scsi/device_handler/scsi_dh_emc.c
@@ -275,7 +275,7 @@ static struct request *get_req(struct scsi_device *sdev, int cmd,
rq = blk_get_request(sdev->request_queue,
(cmd != INQUIRY) ? WRITE : READ, GFP_NOIO);
- if (!rq) {
+ if (IS_ERR(rq)) {
sdev_printk(KERN_INFO, sdev, "get_req: blk_get_request failed");
return NULL;
}
diff --git a/drivers/scsi/device_handler/scsi_dh_hp_sw.c b/drivers/scsi/device_handler/scsi_dh_hp_sw.c
index 084062b..1cf4019 100644
--- a/drivers/scsi/device_handler/scsi_dh_hp_sw.c
+++ b/drivers/scsi/device_handler/scsi_dh_hp_sw.c
@@ -117,7 +117,7 @@ static int hp_sw_tur(struct scsi_device *sdev, struct hp_sw_dh_data *h)
retry:
req = blk_get_request(sdev->request_queue, WRITE, GFP_NOIO);
- if (!req)
+ if (IS_ERR(req))
return SCSI_DH_RES_TEMP_UNAVAIL;
req->cmd_type = REQ_TYPE_BLOCK_PC;
@@ -247,7 +247,7 @@ static int hp_sw_start_stop(struct hp_sw_dh_data *h)
struct request *req;
req = blk_get_request(h->sdev->request_queue, WRITE, GFP_ATOMIC);
- if (!req)
+ if (IS_ERR(req))
return SCSI_DH_RES_TEMP_UNAVAIL;
req->cmd_type = REQ_TYPE_BLOCK_PC;
diff --git a/drivers/scsi/device_handler/scsi_dh_rdac.c b/drivers/scsi/device_handler/scsi_dh_rdac.c
index 69c915a..009bd8f 100644
--- a/drivers/scsi/device_handler/scsi_dh_rdac.c
+++ b/drivers/scsi/device_handler/scsi_dh_rdac.c
@@ -274,7 +274,7 @@ static struct request *get_rdac_req(struct scsi_device *sdev,
rq = blk_get_request(q, rw, GFP_NOIO);
- if (!rq) {
+ if (IS_ERR(rq)) {
sdev_printk(KERN_INFO, sdev,
"get_rdac_req: blk_get_request failed.\n");
return NULL;
diff --git a/drivers/scsi/osd/osd_initiator.c b/drivers/scsi/osd/osd_initiator.c
index d8293f2..b4cd56b 100644
--- a/drivers/scsi/osd/osd_initiator.c
+++ b/drivers/scsi/osd/osd_initiator.c
@@ -1567,8 +1567,8 @@ static struct request *_make_request(struct request_queue *q, bool has_write,
struct request *req;
req = blk_get_request(q, has_write ? WRITE : READ, flags);
- if (unlikely(!req))
- return ERR_PTR(-ENOMEM);
+ if (unlikely(IS_ERR(req)))
+ return req;
return req;
}
diff --git a/drivers/scsi/osst.c b/drivers/scsi/osst.c
index 21883a2..826cda9 100644
--- a/drivers/scsi/osst.c
+++ b/drivers/scsi/osst.c
@@ -362,7 +362,7 @@ static int osst_execute(struct osst_request *SRpnt, const unsigned char *cmd,
int write = (data_direction == DMA_TO_DEVICE);
req = blk_get_request(SRpnt->stp->device->request_queue, write, GFP_KERNEL);
- if (!req)
+ if (IS_ERR(req))
return DRIVER_ERROR << 24;
req->cmd_type = REQ_TYPE_BLOCK_PC;
diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index c1b05a8..7b248fb 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -1635,6 +1635,8 @@ static void scsi_eh_lock_door(struct scsi_device *sdev)
* request becomes available
*/
req = blk_get_request(sdev->request_queue, READ, GFP_KERNEL);
+ if (IS_ERR(req))
+ return;
req->cmd[0] = ALLOW_MEDIUM_REMOVAL;
req->cmd[1] = 0;
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index c31187d..cad055b 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -236,7 +236,7 @@ int scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
int ret = DRIVER_ERROR << 24;
req = blk_get_request(sdev->request_queue, write, __GFP_WAIT);
- if (!req)
+ if (IS_ERR(req))
return ret;
if (bufflen && blk_rq_map_kern(sdev->request_queue, req,
diff --git a/drivers/scsi/scsi_tgt_lib.c b/drivers/scsi/scsi_tgt_lib.c
index 84a1fdf..d300620 100644
--- a/drivers/scsi/scsi_tgt_lib.c
+++ b/drivers/scsi/scsi_tgt_lib.c
@@ -97,7 +97,7 @@ struct scsi_cmnd *scsi_host_get_command(struct Scsi_Host *shost,
* we are in target mode we want the opposite.
*/
rq = blk_get_request(shost->uspace_req_q, !write, gfp_mask);
- if (!rq)
+ if (IS_ERR(rq))
goto free_tcmd;
cmd = __scsi_get_command(shost, gfp_mask);
diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 9f0c465..5d39fec 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -1649,8 +1649,8 @@ static int sg_start_req(Sg_request *srp, unsigned char *cmd)
dxfer_len));
rq = blk_get_request(q, rw, GFP_ATOMIC);
- if (!rq)
- return -ENOMEM;
+ if (IS_ERR(rq))
+ return PTR_ERR(rq);
memcpy(rq->cmd, cmd, hp->cmd_len);
diff --git a/drivers/scsi/st.c b/drivers/scsi/st.c
index 8697447..5fca9cb 100644
--- a/drivers/scsi/st.c
+++ b/drivers/scsi/st.c
@@ -481,7 +481,7 @@ static int st_scsi_execute(struct st_request *SRpnt, const unsigned char *cmd,
req = blk_get_request(SRpnt->stp->device->request_queue, write,
GFP_KERNEL);
- if (!req)
+ if (IS_ERR(req))
return DRIVER_ERROR << 24;
req->cmd_type = REQ_TYPE_BLOCK_PC;
diff --git a/drivers/target/target_core_pscsi.c b/drivers/target/target_core_pscsi.c
index 82e78d7..8cd953a 100644
--- a/drivers/target/target_core_pscsi.c
+++ b/drivers/target/target_core_pscsi.c
@@ -1045,9 +1045,9 @@ pscsi_execute_cmd(struct se_cmd *cmd)
req = blk_get_request(pdv->pdv_sd->request_queue,
(data_direction == DMA_TO_DEVICE),
GFP_KERNEL);
- if (!req || IS_ERR(req)) {
+ if (IS_ERR(req)) {
pr_err("PSCSI: blk_get_request() failed: %ld\n",
- req ? IS_ERR(req) : -ENOMEM);
+ PTR_ERR(req));
ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
goto fail;
}
--
1.8.1.4
--
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