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staging: unisys: visorhba: fail gracefully for thread creation failures

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Previously, if visorhba ever failed to create its thread, it would have
subsequently attempted to do a kthread_stop() on an invalid task_struct
pointer.  This was fixed via the new visor_thread_stop() function, which
validates the task_struct pointer before doing the kthread_stop().

Also, the other thread-related fields in visor_thread_info (has_stopped
and id) were not being used, so visor_thead_info was just removed.

We also now spit out an error message if thread creation fails.

Signed-off-by: Tim Sell <Timothy.Sell@unisys.com>
Signed-off-by: David Kershner <david.kershner@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Tim Sell 2016-05-06 13:11:20 -04:00 committed by Greg Kroah-Hartman
parent 77c9a4ae81
commit 0fab0f4fcb
1 changed files with 28 additions and 26 deletions
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54
drivers/staging/unisys/visorhba/visorhba_main.c
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@ -85,12 +85,6 @@ static struct visor_driver visorhba_driver = {
MODULE_DEVICE_TABLE(visorbus, visorhba_channel_types);
MODULE_ALIAS("visorbus:" SPAR_VHBA_CHANNEL_PROTOCOL_UUID_STR);
struct visor_thread_info {
struct task_struct *task;
struct completion has_stopped;
int id;
};
struct visordisk_info {
u32 valid;
u32 channel, id, lun; /* Disk Path */
@ -137,7 +131,7 @@ struct visorhba_devdata {
struct visordisk_info head;
unsigned int max_buff_len;
int devnum;
struct visor_thread_info threadinfo;
struct task_struct *thread;
int thread_wait_ms;
};
@ -154,28 +148,36 @@ static struct visorhba_devices_open visorhbas_open[VISORHBA_OPEN_MAX];
(iter->lun == match->lun))
/**
* visor_thread_start - starts a thread for the device
* @thrinfo: The thread to start
* @threadfn: Function the thread starts
* @thrcontext: Context to pass to the thread, i.e. devdata
* @name: string describing name of thread
*
* Starts a thread for the device.
*
* Return 0 on success;
* Return the task_struct * denoting the thread on success,
* or NULL on failure
*/
static int visor_thread_start(struct visor_thread_info *thrinfo,
int (*threadfn)(void *),
void *thrcontext, char *name)
static struct task_struct *visor_thread_start
(int (*threadfn)(void *), void *thrcontext, char *name)
{
/* used to stop the thread */
init_completion(&thrinfo->has_stopped);
thrinfo->task = kthread_run(threadfn, thrcontext, "%s", name);
if (IS_ERR(thrinfo->task)) {
thrinfo->id = 0;
return PTR_ERR(thrinfo->task);
struct task_struct *task;
task = kthread_run(threadfn, thrcontext, "%s", name);
if (IS_ERR(task)) {
pr_err("visorbus failed to start thread\n");
return NULL;
}
thrinfo->id = thrinfo->task->pid;
return 0;
return task;
}
/**
* visor_thread_stop - stops the thread if it is running
*/
static void visor_thread_stop(struct task_struct *task)
{
if (!task)
return; /* no thread running */
kthread_stop(task);
}
/**
@ -683,7 +685,7 @@ static void visorhba_serverdown_complete(struct visorhba_devdata *devdata)
/* Stop using the IOVM response queue (queue should be drained
* by the end)
*/
kthread_stop(devdata->threadinfo.task);
visor_thread_stop(devdata->thread);
/* Fail commands that weren't completed */
spin_lock_irqsave(&devdata->privlock, flags);
@ -1082,8 +1084,8 @@ static int visorhba_resume(struct visor_device *dev,
if (devdata->serverdown && !devdata->serverchangingstate)
devdata->serverchangingstate = true;
visor_thread_start(&devdata->threadinfo, process_incoming_rsps,
devdata, "vhba_incming");
devdata->thread = visor_thread_start(process_incoming_rsps, devdata,
"vhba_incming");
devdata->serverdown = false;
devdata->serverchangingstate = false;
@ -1159,8 +1161,8 @@ static int visorhba_probe(struct visor_device *dev)
goto err_scsi_remove_host;
devdata->thread_wait_ms = 2;
visor_thread_start(&devdata->threadinfo, process_incoming_rsps,
devdata, "vhba_incoming");
devdata->thread = visor_thread_start(process_incoming_rsps, devdata,
"vhba_incoming");
scsi_scan_host(scsihost);
@ -1190,7 +1192,7 @@ static void visorhba_remove(struct visor_device *dev)
return;
scsihost = devdata->scsihost;
kthread_stop(devdata->threadinfo.task);
visor_thread_stop(devdata->thread);
scsi_remove_host(scsihost);
scsi_host_put(scsihost);