From 50ec5babd3b9da274ac3e0d5ca0c4772e3c7bc8d Mon Sep 17 00:00:00 2001 From: Santosh Nayak Date: Sun, 26 Feb 2012 19:05:03 +0530 Subject: [PATCH] [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: Santosh Nayak Acked-by: Jack Wang Signed-off-by: James Bottomley --- drivers/scsi/pm8001/pm8001_hwi.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/scsi/pm8001/pm8001_hwi.c b/drivers/scsi/pm8001/pm8001_hwi.c index 871d1c3f..dc28ae1 100644 --- a/drivers/scsi/pm8001/pm8001_hwi.c +++ b/drivers/scsi/pm8001/pm8001_hwi.c @@ -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; } -- 2.7.4