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Commit 0fab0f4f authored by Tim Sell's avatar Tim Sell Committed by Greg Kroah-Hartman
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staging: unisys: visorhba: fail gracefully for thread creation failures 



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: default avatarTim Sell <Timothy.Sell@unisys.com>
Signed-off-by: default avatarDavid Kershner <david.kershner@unisys.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 77c9a4ae

drivers/staging/unisys/visorhba/visorhba_main.c

+28 −26
Original line number Diff line number Diff line
@@ -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);