Commit 817a7c99 authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Martin K. Petersen
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scsi: message: fusion: Remove in_interrupt() usage in mptsas_cleanup_fw_event_q() 

mptsas_cleanup_fw_event_q() uses in_interrupt() to determine if it is safe
to cancel a worker item.

Aside of that in_interrupt() is deprecated as it does not provide what the
name suggests. It covers more than hard/soft interrupt servicing context
and is semantically ill defined.

Looking closer there are a few problems with the current construct:

 - It could be invoked from an interrupt handler / non-blocking context
   because cancel_delayed_work() has no such restriction. Also,
   mptsas_free_fw_event() has no such restriction.

 - The list is accessed unlocked. It may dequeue a valid work-item but at
   the time of invoking cancel_delayed_work() the memory may be released or
   reused because the worker has already run.

mptsas_cleanup_fw_event_q() is invoked via mptsas_shutdown() which is
always invoked from preemtible context on device shutdown.  It is also
invoked via mptsas_ioc_reset(, MPT_IOC_POST_RESET) which is a
MptResetHandlers callback. The only caller here are mpt_SoftResetHandler(),
mpt_HardResetHandler() and mpt_Soft_Hard_ResetHandler(). All these
functions have a `sleepFlag' argument and each caller uses caller uses
`CAN_SLEEP' here and according to current documentation: | @sleepFlag:
Indicates if sleep or schedule must be called

So it is safe to sleep.

Add mptsas_hotplug_event::users member. Initialize it to one by default so
mptsas_free_fw_event() will free the memory.  mptsas_cleanup_fw_event_q()
will increment its value for items it dequeues and then it may keep a
pointer after dropping the lock.  Invoke cancel_delayed_work_sync() to
cancel the work item and wait if the worker is currently busy. Free the
memory afterwards since it owns the last reference to it.

Link: https://lore.kernel.org/r/20201126132952.2287996-15-bigeasy@linutronix.de


Cc: Sathya Prakash <sathya.prakash@broadcom.com>
Cc: Sreekanth Reddy <sreekanth.reddy@broadcom.com>
Cc: Suganath Prabu Subramani <suganath-prabu.subramani@broadcom.com>
Cc: MPT-FusionLinux.pdl@broadcom.com
Reviewed-by: default avatarDaniel Wagner <dwagner@suse.de>
Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent b8a51443

drivers/message/fusion/mptsas.c

+35 −10
Original line number Diff line number Diff line
@@ -289,6 +289,7 @@ mptsas_add_fw_event(MPT_ADAPTER *ioc, struct fw_event_work *fw_event, 


	spin_lock_irqsave(&ioc->fw_event_lock, flags);

	list_add_tail(&fw_event->list, &ioc->fw_event_list);

	fw_event->users = 1;

	INIT_DELAYED_WORK(&fw_event->work, mptsas_firmware_event_work);

	devtprintk(ioc, printk(MYIOC_s_DEBUG_FMT "%s: add (fw_event=0x%p)"

		"on cpuid %d\n", ioc->name, __func__,
@@ -314,6 +315,15 @@ mptsas_requeue_fw_event(MPT_ADAPTER *ioc, struct fw_event_work *fw_event, 
	spin_unlock_irqrestore(&ioc->fw_event_lock, flags);

}



static void __mptsas_free_fw_event(MPT_ADAPTER *ioc,

				   struct fw_event_work *fw_event)

{

	devtprintk(ioc, printk(MYIOC_s_DEBUG_FMT "%s: kfree (fw_event=0x%p)\n",

	    ioc->name, __func__, fw_event));

	list_del(&fw_event->list);

	kfree(fw_event);

}



/* free memory associated to a sas firmware event */

static void

mptsas_free_fw_event(MPT_ADAPTER *ioc, struct fw_event_work *fw_event)
@@ -321,10 +331,9 @@ mptsas_free_fw_event(MPT_ADAPTER *ioc, struct fw_event_work *fw_event) 
	unsigned long flags;



	spin_lock_irqsave(&ioc->fw_event_lock, flags);

	devtprintk(ioc, printk(MYIOC_s_DEBUG_FMT "%s: kfree (fw_event=0x%p)\n",

	    ioc->name, __func__, fw_event));

	list_del(&fw_event->list);

	kfree(fw_event);

	fw_event->users--;

	if (!fw_event->users)

		__mptsas_free_fw_event(ioc, fw_event);

	spin_unlock_irqrestore(&ioc->fw_event_lock, flags);

}
@@ -333,9 +342,10 @@ mptsas_free_fw_event(MPT_ADAPTER *ioc, struct fw_event_work *fw_event) 
static void

mptsas_cleanup_fw_event_q(MPT_ADAPTER *ioc)

{

	struct fw_event_work *fw_event, *next;

	struct fw_event_work *fw_event;

	struct mptsas_target_reset_event *target_reset_list, *n;

	MPT_SCSI_HOST	*hd = shost_priv(ioc->sh);

	unsigned long flags;



	/* flush the target_reset_list */

	if (!list_empty(&hd->target_reset_list)) {
@@ -350,14 +360,29 @@ mptsas_cleanup_fw_event_q(MPT_ADAPTER *ioc) 
		}

	}



	if (list_empty(&ioc->fw_event_list) ||

	     !ioc->fw_event_q || in_interrupt())

	if (list_empty(&ioc->fw_event_list) || !ioc->fw_event_q)

		return;



	list_for_each_entry_safe(fw_event, next, &ioc->fw_event_list, list) {

		if (cancel_delayed_work(&fw_event->work))

			mptsas_free_fw_event(ioc, fw_event);

	spin_lock_irqsave(&ioc->fw_event_lock, flags);



	while (!list_empty(&ioc->fw_event_list)) {

		bool canceled = false;



		fw_event = list_first_entry(&ioc->fw_event_list,

					    struct fw_event_work, list);

		fw_event->users++;

		spin_unlock_irqrestore(&ioc->fw_event_lock, flags);

		if (cancel_delayed_work_sync(&fw_event->work))

			canceled = true;



		spin_lock_irqsave(&ioc->fw_event_lock, flags);

		if (canceled)

			fw_event->users--;

		fw_event->users--;

		WARN_ON_ONCE(fw_event->users);

		__mptsas_free_fw_event(ioc, fw_event);

	}

	spin_unlock_irqrestore(&ioc->fw_event_lock, flags);

}

drivers/message/fusion/mptsas.h

+1 −0
Original line number Diff line number Diff line
@@ -107,6 +107,7 @@ struct mptsas_hotplug_event { 
struct fw_event_work {

	struct list_head 	list;

	struct delayed_work	 work;

	int			users;

	MPT_ADAPTER	*ioc;

	u32			event;

	u8			retries;