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Commit 50ec5bab authored by Santosh Nayak's avatar Santosh Nayak Committed by James Bottomley
Browse files

[SCSI] pm8001: Fix possible racing condition. 



There is a possble racing scenario.

'process_oq' is called by two routines, as shown below.

pm8001_8001_dispatch = {
         .......

        .isr             = pm8001_chip_isr --> process_oq,// A
        .isr_process_oq  = process_oq,                   //  B
        .....
}

process_oq() --> process_one_iomb() --> mpi_sata_completion()

In 'mpi_sata_completion', "pm8001_ha->lock" is first released.
It means lock is taken before,  which is true for
the context A, as 'pm8001_ha->lock' is taken in 'pm8001_chip_isr()'

But for context B there is no lock taken before and pm8001_ha->lock
is unlocked in 'mpi_sata_completion()'. This may unlock the lock
taken in context A. Possible racing ??

If 'pm8001_ha->lock' is taken in 'process_oq()' instead of
'pm8001_chip_isr' then the above issue can be avoided.

Signed-off-by: default avatarSantosh Nayak <santoshprasadnayak@gmail.com>
Acked-by: default avatarJack Wang <jack_wang@usish.com>
Signed-off-by: default avatarJames Bottomley <JBottomley@Parallels.com>
parent bdaefbf5

drivers/scsi/pm8001/pm8001_hwi.c

+3 −3
Original line number Diff line number Diff line
@@ -3869,7 +3869,9 @@ static int process_oq(struct pm8001_hba_info *pm8001_ha) 
	void *pMsg1 = NULL;

	u8 bc = 0;

	u32 ret = MPI_IO_STATUS_FAIL;

	unsigned long flags;



	spin_lock_irqsave(&pm8001_ha->lock, flags);

	circularQ = &pm8001_ha->outbnd_q_tbl[0];

	do {

		ret = mpi_msg_consume(pm8001_ha, circularQ, &pMsg1, &bc);
@@ -3890,6 +3892,7 @@ static int process_oq(struct pm8001_hba_info *pm8001_ha) 
				break;

		}

	} while (1);

	spin_unlock_irqrestore(&pm8001_ha->lock, flags);

	return ret;

}
@@ -4295,12 +4298,9 @@ static u32 pm8001_chip_is_our_interupt(struct pm8001_hba_info *pm8001_ha) 
static irqreturn_t

pm8001_chip_isr(struct pm8001_hba_info *pm8001_ha)

{

	unsigned long flags;

	spin_lock_irqsave(&pm8001_ha->lock, flags);

	pm8001_chip_interrupt_disable(pm8001_ha);

	process_oq(pm8001_ha);

	pm8001_chip_interrupt_enable(pm8001_ha);

	spin_unlock_irqrestore(&pm8001_ha->lock, flags);

	return IRQ_HANDLED;

}