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SubjectRE: [PATCH 2/2] [SCSI] pm8001: Fix possible racing codition.
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Infact , process_oq is only called in pm8001_chip_isr, but this patch looks
OK for me. Move down the lock to process_oq is OK.

Thanks for fix.
Acked-by : Jack Wang <jack_wang@usish.com>

> From: Santosh Nayak <santoshprasadnayak@gmail.com>
>
> 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: Santosh Nayak <santoshprasadnayak@gmail.com>
> ---
> drivers/scsi/pm8001/pm8001_hwi.c | 6 +++---
> 1 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/scsi/pm8001/pm8001_hwi.c
> b/drivers/scsi/pm8001/pm8001_hwi.c
> index 838e3e2..6d9973b 100644
> --- a/drivers/scsi/pm8001/pm8001_hwi.c
> +++ b/drivers/scsi/pm8001/pm8001_hwi.c
> @@ -3663,7 +3663,9 @@ static int process_oq(struct pm8001_hba_info
*pm8001_ha)
> void *pMsg1 = NULL;
> u8 uninitialized_var(bc);
> 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);
> @@ -3682,6 +3684,7 @@ static int process_oq(struct pm8001_hba_info
*pm8001_ha)
> break;
> }
> } while (1);
> + spin_unlock_irqrestore(&pm8001_ha->lock, flags);
> return ret;
> }
>
> @@ -4087,12 +4090,9 @@ 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;
> }
>
> --
> 1.7.4.4
>
> --
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