From: Hannes Reinecke <hare@suse.de>
To: James Bottomley <jbottomley@parallels.com>
Cc: Christoph Hellwig <hch@infradead.org>,
linux-scsi@vger.kernel.org, Ren Mingxin <renmx@cn.fujitsu.com>,
Joern Engel <joern@logfs.org>,
James Smart <james.smart@emulex.com>,
Hannes Reinecke <hare@suse.de>
Subject: [PATCH 3/5] scsi: Unlock accesses to eh_deadline
Date: Tue, 5 Nov 2013 08:05:43 +0100 [thread overview]
Message-ID: <1383635145-112651-4-git-send-email-hare@suse.de> (raw)
In-Reply-To: <1383635145-112651-1-git-send-email-hare@suse.de>
32bit accesses are guaranteed to be atomic, so we can remove
the spinlock when checking for eh_deadline. We only need to
make sure to catch any updates which might happened during
the call to time_before(); if so we just recheck with the
correct value.
Signed-off-by: Hannes Reinecke <hare@suse.de>
---
drivers/scsi/scsi_error.c | 44 +++++++++-----------------------------------
1 file changed, 9 insertions(+), 35 deletions(-)
diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 7eecbb5..a3f8988 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -94,8 +94,15 @@ static int scsi_host_eh_past_deadline(struct Scsi_Host *shost)
if (!shost->last_reset || !shost->eh_deadline)
return 0;
- if (time_before(jiffies,
- shost->last_reset + shost->eh_deadline))
+ /*
+ * 32bit accesses are guaranteed to be atomic
+ * (on all supported architectures), so instead
+ * of using a spinlock we can as well double check
+ * if eh_deadline has been unset during the
+ * time_before call.
+ */
+ if (time_before(jiffies, shost->last_reset + shost->eh_deadline) &&
+ shost->eh_deadline != 0)
return 0;
return 1;
@@ -111,18 +118,14 @@ scmd_eh_abort_handler(struct work_struct *work)
struct scsi_cmnd *scmd =
container_of(work, struct scsi_cmnd, abort_work.work);
struct scsi_device *sdev = scmd->device;
- unsigned long flags;
int rtn;
- spin_lock_irqsave(sdev->host->host_lock, flags);
if (scsi_host_eh_past_deadline(sdev->host)) {
- spin_unlock_irqrestore(sdev->host->host_lock, flags);
SCSI_LOG_ERROR_RECOVERY(3,
scmd_printk(KERN_INFO, scmd,
"scmd %p eh timeout, not aborting\n",
scmd));
} else {
- spin_unlock_irqrestore(sdev->host->host_lock, flags);
SCSI_LOG_ERROR_RECOVERY(3,
scmd_printk(KERN_INFO, scmd,
"aborting command %p\n", scmd));
@@ -1132,7 +1135,6 @@ int scsi_eh_get_sense(struct list_head *work_q,
struct scsi_cmnd *scmd, *next;
struct Scsi_Host *shost;
int rtn;
- unsigned long flags;
list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
if ((scmd->eh_eflags & SCSI_EH_CANCEL_CMD) ||
@@ -1140,16 +1142,13 @@ int scsi_eh_get_sense(struct list_head *work_q,
continue;
shost = scmd->device->host;
- spin_lock_irqsave(shost->host_lock, flags);
if (scsi_host_eh_past_deadline(shost)) {
- spin_unlock_irqrestore(shost->host_lock, flags);
SCSI_LOG_ERROR_RECOVERY(3,
shost_printk(KERN_INFO, shost,
"skip %s, past eh deadline\n",
__func__));
break;
}
- spin_unlock_irqrestore(shost->host_lock, flags);
SCSI_LOG_ERROR_RECOVERY(2, scmd_printk(KERN_INFO, scmd,
"%s: requesting sense\n",
current->comm));
@@ -1235,26 +1234,21 @@ static int scsi_eh_test_devices(struct list_head *cmd_list,
struct scsi_cmnd *scmd, *next;
struct scsi_device *sdev;
int finish_cmds;
- unsigned long flags;
while (!list_empty(cmd_list)) {
scmd = list_entry(cmd_list->next, struct scsi_cmnd, eh_entry);
sdev = scmd->device;
if (!try_stu) {
- spin_lock_irqsave(sdev->host->host_lock, flags);
if (scsi_host_eh_past_deadline(sdev->host)) {
/* Push items back onto work_q */
list_splice_init(cmd_list, work_q);
- spin_unlock_irqrestore(sdev->host->host_lock,
- flags);
SCSI_LOG_ERROR_RECOVERY(3,
shost_printk(KERN_INFO, sdev->host,
"skip %s, past eh deadline",
__func__));
break;
}
- spin_unlock_irqrestore(sdev->host->host_lock, flags);
}
finish_cmds = !scsi_device_online(scmd->device) ||
@@ -1295,15 +1289,12 @@ static int scsi_eh_abort_cmds(struct list_head *work_q,
LIST_HEAD(check_list);
int rtn;
struct Scsi_Host *shost;
- unsigned long flags;
list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
if (!(scmd->eh_eflags & SCSI_EH_CANCEL_CMD))
continue;
shost = scmd->device->host;
- spin_lock_irqsave(shost->host_lock, flags);
if (scsi_host_eh_past_deadline(shost)) {
- spin_unlock_irqrestore(shost->host_lock, flags);
list_splice_init(&check_list, work_q);
SCSI_LOG_ERROR_RECOVERY(3,
shost_printk(KERN_INFO, shost,
@@ -1311,7 +1302,6 @@ static int scsi_eh_abort_cmds(struct list_head *work_q,
__func__));
return list_empty(work_q);
}
- spin_unlock_irqrestore(shost->host_lock, flags);
SCSI_LOG_ERROR_RECOVERY(3, printk("%s: aborting cmd:"
"0x%p\n", current->comm,
scmd));
@@ -1375,19 +1365,15 @@ static int scsi_eh_stu(struct Scsi_Host *shost,
{
struct scsi_cmnd *scmd, *stu_scmd, *next;
struct scsi_device *sdev;
- unsigned long flags;
shost_for_each_device(sdev, shost) {
- spin_lock_irqsave(shost->host_lock, flags);
if (scsi_host_eh_past_deadline(shost)) {
- spin_unlock_irqrestore(shost->host_lock, flags);
SCSI_LOG_ERROR_RECOVERY(3,
shost_printk(KERN_INFO, shost,
"skip %s, past eh deadline\n",
__func__));
break;
}
- spin_unlock_irqrestore(shost->host_lock, flags);
stu_scmd = NULL;
list_for_each_entry(scmd, work_q, eh_entry)
if (scmd->device == sdev && SCSI_SENSE_VALID(scmd) &&
@@ -1441,20 +1427,16 @@ static int scsi_eh_bus_device_reset(struct Scsi_Host *shost,
{
struct scsi_cmnd *scmd, *bdr_scmd, *next;
struct scsi_device *sdev;
- unsigned long flags;
int rtn;
shost_for_each_device(sdev, shost) {
- spin_lock_irqsave(shost->host_lock, flags);
if (scsi_host_eh_past_deadline(shost)) {
- spin_unlock_irqrestore(shost->host_lock, flags);
SCSI_LOG_ERROR_RECOVERY(3,
shost_printk(KERN_INFO, shost,
"skip %s, past eh deadline\n",
__func__));
break;
}
- spin_unlock_irqrestore(shost->host_lock, flags);
bdr_scmd = NULL;
list_for_each_entry(scmd, work_q, eh_entry)
if (scmd->device == sdev) {
@@ -1515,11 +1497,8 @@ static int scsi_eh_target_reset(struct Scsi_Host *shost,
struct scsi_cmnd *next, *scmd;
int rtn;
unsigned int id;
- unsigned long flags;
- spin_lock_irqsave(shost->host_lock, flags);
if (scsi_host_eh_past_deadline(shost)) {
- spin_unlock_irqrestore(shost->host_lock, flags);
/* push back on work queue for further processing */
list_splice_init(&check_list, work_q);
list_splice_init(&tmp_list, work_q);
@@ -1529,7 +1508,6 @@ static int scsi_eh_target_reset(struct Scsi_Host *shost,
__func__));
return list_empty(work_q);
}
- spin_unlock_irqrestore(shost->host_lock, flags);
scmd = list_entry(tmp_list.next, struct scsi_cmnd, eh_entry);
id = scmd_id(scmd);
@@ -1574,7 +1552,6 @@ static int scsi_eh_bus_reset(struct Scsi_Host *shost,
LIST_HEAD(check_list);
unsigned int channel;
int rtn;
- unsigned long flags;
/*
* we really want to loop over the various channels, and do this on
@@ -1584,9 +1561,7 @@ static int scsi_eh_bus_reset(struct Scsi_Host *shost,
*/
for (channel = 0; channel <= shost->max_channel; channel++) {
- spin_lock_irqsave(shost->host_lock, flags);
if (scsi_host_eh_past_deadline(shost)) {
- spin_unlock_irqrestore(shost->host_lock, flags);
list_splice_init(&check_list, work_q);
SCSI_LOG_ERROR_RECOVERY(3,
shost_printk(KERN_INFO, shost,
@@ -1594,7 +1569,6 @@ static int scsi_eh_bus_reset(struct Scsi_Host *shost,
__func__));
return list_empty(work_q);
}
- spin_unlock_irqrestore(shost->host_lock, flags);
chan_scmd = NULL;
list_for_each_entry(scmd, work_q, eh_entry) {
--
1.7.12.4
next prev parent reply other threads:[~2013-11-05 7:05 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-05 7:05 [PATCHv10 0/5] New EH command timeout handler Hannes Reinecke
2013-11-05 7:05 ` [PATCH 1/5] scsi: Fix erratic device offline during EH Hannes Reinecke
2013-11-05 7:05 ` [PATCH 2/5] scsi: improved eh timeout handler Hannes Reinecke
2013-11-05 19:19 ` Mike Christie
2013-11-06 6:48 ` Hannes Reinecke
2013-11-06 17:23 ` Mike Christie
2013-11-07 6:45 ` Hannes Reinecke
2013-11-07 18:33 ` Douglas Gilbert
2013-11-08 15:54 ` Hannes Reinecke
2013-11-09 8:35 ` James Bottomley
2013-11-09 15:27 ` Hannes Reinecke
2013-11-06 14:47 ` Christoph Hellwig
2013-11-07 6:42 ` Hannes Reinecke
2013-11-05 7:05 ` Hannes Reinecke [this message]
2013-11-05 7:05 ` [PATCH 4/5] scsi: Set the minimum valid value of 'eh_deadline' as 0 Hannes Reinecke
2013-11-05 7:05 ` [PATCH 5/5] scsi: Update documentation Hannes Reinecke
-- strict thread matches above, loose matches on Subject: below --
2013-11-11 12:44 [PATCHv11 0/5] New EH command timeout handler Hannes Reinecke
2013-11-11 12:44 ` [PATCH 3/5] scsi: Unlock accesses to eh_deadline Hannes Reinecke
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