From 76ad3e5956bf0bc8871ebd19ebda03f2287c966a Mon Sep 17 00:00:00 2001 From: Hannes Reinecke Date: Mon, 11 Nov 2013 13:44:55 +0100 Subject: [PATCH] [SCSI] Unlock accesses to eh_deadline 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 Signed-off-by: James Bottomley --- 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 3dd0402..4e4824b 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) { -- 2.7.4