A SCSI LLD may start cleaning up host resources as soon as
scsi_remove_host() returns. These host resources may be needed by
the LLD in an implementation of one of the eh_* functions. So if
one of the eh_* functions is in progress when scsi_remove_host()
is invoked, wait until the eh_* function has finished. Also, do
not invoke any of the eh_* functions after scsi_remove_host() has
started. Remove Scsi_Host.tmf_in_progress because it is now
superfluous.
Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxx>
Cc: Mike Christie <michaelc@xxxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
---
drivers/scsi/hosts.c | 6 ++++
drivers/scsi/scsi_error.c | 86 ++++++++++++++++++++++++++++++++++++++-------
include/scsi/scsi_host.h | 6 ++--
3 files changed, 81 insertions(+), 17 deletions(-)
diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index 034a567..17e2ccb 100644
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -176,6 +176,12 @@ void scsi_remove_host(struct Scsi_Host *shost)
BUG_ON(scsi_host_set_state(shost, SHOST_DEL_RECOVERY));
spin_unlock_irq(shost->host_lock);
+ /*
+ * Wait until the error handler has finished invoking LLD callbacks
+ * before allowing the LLD to proceed.
+ */
+ wait_event(shost->host_wait, shost->eh_active == 0);
+
transport_unregister_device(&shost->shost_gendev);
device_unregister(&shost->shost_dev);
device_del(&shost->shost_gendev);
diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index c1b05a8..b739afe 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -536,8 +536,53 @@ static void scsi_eh_done(struct scsi_cmnd *scmd)
}
/**
+ * scsi_begin_eh - start host-related error handling
+ *
+ * Must be called before invoking an LLD callback function to avoid that
+ * scsi_remove_host() returns while one of these callback functions is in
+ * progress.
+ *
+ * Returns 0 if invoking an eh_* function is allowed and a negative value if
+ * not. If this function returns 0 then scsi_end_eh() must be called
+ * eventually.
+ */
+static int scsi_begin_eh(struct Scsi_Host *host)
+{
+ int res;
+
+ spin_lock_irq(host->host_lock);
+ switch (host->shost_state) {
+ case SHOST_DEL:
+ case SHOST_DEL_RECOVERY:
+ res = -ENODEV;
+ break;
+ default:
+ WARN_ON_ONCE(host->eh_active < 0);
+ host->eh_active++;
+ res = 0;
+ break;
+ }
+ spin_unlock_irq(host->host_lock);
+
+ return res;
+}
+
+/**
+ * scsi_end_eh - finish host-related error handling
+ */
+static void scsi_end_eh(struct Scsi_Host *host)
+{
+ spin_lock_irq(host->host_lock);
+ host->eh_active--;
+ WARN_ON_ONCE(host->eh_active < 0);
+ if (host->eh_active == 0)
+ wake_up(&host->host_wait);
+ spin_unlock_irq(host->host_lock);
+}
+
+/**
* scsi_try_host_reset - ask host adapter to reset itself
- * @scmd: SCSI cmd to send hsot reset.
+ * @scmd: SCSI cmd to send host reset.
*/
static int scsi_try_host_reset(struct scsi_cmnd *scmd)
{
@@ -552,6 +597,9 @@ static int scsi_try_host_reset(struct scsi_cmnd *scmd)
if (!hostt->eh_host_reset_handler)
return FAILED;
+ if (scsi_begin_eh(host))
+ return FAST_IO_FAIL;
+
rtn = hostt->eh_host_reset_handler(scmd);
if (rtn == SUCCESS) {
@@ -561,6 +609,7 @@ static int scsi_try_host_reset(struct scsi_cmnd *scmd)
scsi_report_bus_reset(host, scmd_channel(scmd));
spin_unlock_irqrestore(host->host_lock, flags);
}
+ scsi_end_eh(host);
return rtn;
}
@@ -582,6 +631,9 @@ static int scsi_try_bus_reset(struct scsi_cmnd *scmd)
if (!hostt->eh_bus_reset_handler)
return FAILED;
+ if (scsi_begin_eh(host))
+ return FAST_IO_FAIL;
+
rtn = hostt->eh_bus_reset_handler(scmd);
if (rtn == SUCCESS) {
@@ -591,6 +643,7 @@ static int scsi_try_bus_reset(struct scsi_cmnd *scmd)
scsi_report_bus_reset(host, scmd_channel(scmd));
spin_unlock_irqrestore(host->host_lock, flags);
}
+ scsi_end_eh(host);
return rtn;
}
@@ -621,6 +674,9 @@ static int scsi_try_target_reset(struct scsi_cmnd *scmd)
if (!hostt->eh_target_reset_handler)
return FAILED;
+ if (scsi_begin_eh(host))
+ return FAST_IO_FAIL;
+
rtn = hostt->eh_target_reset_handler(scmd);
if (rtn == SUCCESS) {
spin_lock_irqsave(host->host_lock, flags);
@@ -628,6 +684,7 @@ static int scsi_try_target_reset(struct scsi_cmnd *scmd)
__scsi_report_device_reset);
spin_unlock_irqrestore(host->host_lock, flags);
}
+ scsi_end_eh(host);
return rtn;
}
@@ -645,14 +702,20 @@ static int scsi_try_target_reset(struct scsi_cmnd *scmd)
static int scsi_try_bus_device_reset(struct scsi_cmnd *scmd)
{
int rtn;
- struct scsi_host_template *hostt = scmd->device->host->hostt;
+ struct Scsi_Host *host = scmd->device->host;
+ struct scsi_host_template *hostt = host->hostt;
if (!hostt->eh_device_reset_handler)
return FAILED;
+ if (scsi_begin_eh(host))
+ return FAST_IO_FAIL;
+
rtn = hostt->eh_device_reset_handler(scmd);
if (rtn == SUCCESS)
__scsi_report_device_reset(scmd->device, NULL);
+ scsi_end_eh(host);
+
return rtn;
}
@@ -795,6 +858,9 @@ static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd,
struct scsi_eh_save ses;
int rtn;
+ if (scsi_begin_eh(shost))
+ return FAILED;
+
scsi_eh_prep_cmnd(scmd, &ses, cmnd, cmnd_size, sense_bytes);
shost->eh_action = &done;
@@ -850,6 +916,8 @@ static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd,
rtn = sdrv->eh_action(scmd, cmnd, cmnd_size, rtn);
}
+ scsi_end_eh(shost);
+
return rtn;
}
@@ -1877,6 +1945,9 @@ int scsi_error_handler(void *data)
}
__set_current_state(TASK_RUNNING);
+ WARN_ONCE(shost->eh_active, "scsi_eh_%d: eh_active = %d\n",
+ shost->host_no, shost->eh_active);
+
SCSI_LOG_ERROR_RECOVERY(1,
printk("Error handler scsi_eh_%d exiting\n", shost->host_no));
shost->ehandler = NULL;
@@ -1973,7 +2044,6 @@ scsi_reset_provider(struct scsi_device *dev, int flag)
struct scsi_cmnd *scmd;
struct Scsi_Host *shost = dev->host;
struct request req;
- unsigned long flags;
int rtn;
if (scsi_autopm_get_host(shost) < 0)
@@ -1992,10 +2062,6 @@ scsi_reset_provider(struct scsi_device *dev, int flag)
scmd->sc_data_direction = DMA_BIDIRECTIONAL;
- spin_lock_irqsave(shost->host_lock, flags);
- shost->tmf_in_progress = 1;
- spin_unlock_irqrestore(shost->host_lock, flags);
-
switch (flag) {
case SCSI_TRY_RESET_DEVICE:
rtn = scsi_try_bus_device_reset(scmd);
@@ -2019,10 +2085,6 @@ scsi_reset_provider(struct scsi_device *dev, int flag)
rtn = FAILED;
}
- spin_lock_irqsave(shost->host_lock, flags);
- shost->tmf_in_progress = 0;
- spin_unlock_irqrestore(shost->host_lock, flags);
-
/*
* be sure to wake up anyone who was sleeping or had their queue
* suspended while we performed the TMF.
@@ -2031,8 +2093,6 @@ scsi_reset_provider(struct scsi_device *dev, int flag)
printk("%s: waking up host to restart after TMF\n",
__func__));
- wake_up(&shost->host_wait);
-
scsi_run_host_queues(shost);
scsi_next_command(scmd);
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 2b6956e..efd5e0c7 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -576,6 +576,7 @@ struct Scsi_Host {
struct task_struct * ehandler; /* Error recovery thread. */
struct completion * eh_action; /* Wait for specific actions on the
host. */
+ int eh_active;
wait_queue_head_t host_wait;
struct scsi_host_template *hostt;
struct scsi_transport_template *transportt;
@@ -663,9 +664,6 @@ struct Scsi_Host {
*/
unsigned ordered_tag:1;
- /* Task mgmt function in progress */
- unsigned tmf_in_progress:1;
-
/* Asynchronous scan in progress */
unsigned async_scan:1;
@@ -769,7 +767,7 @@ static inline int scsi_host_in_recovery(struct Scsi_Host *shost)
return shost->shost_state == SHOST_RECOVERY ||
shost->shost_state == SHOST_CANCEL_RECOVERY ||
shost->shost_state == SHOST_DEL_RECOVERY ||
- shost->tmf_in_progress;
+ shost->eh_active;
}
extern int scsi_queue_work(struct Scsi_Host *, struct work_struct *);
--
1.7.10.4
--
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