lkml.org 
[lkml]   [2012]   [Feb]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    SubjectRe: [PATCH 1/2] [SCSI] pm8001: Fix bogus interrupt state flag issue.
    From
     In 'mpi_sata_completion'
    the first call for 'spin_unlock_irqrestore()' is with flags=0,
    which is as good as 'spin_unlock_irq()' ( unconditional interrupt
    enabling). If intention of the developer is to enable the interrupt during
    execution of ' mpi_sata_completion' , then the code changes in the patch
    looks ok.

    If interrupt should not be enabled during execution of
    'mpi_sata_completion' then
    we can use simple spin_lock and spin_unlock.


    regards
    santosh


    On Sun, Feb 26, 2012 at 8:37 PM, Dan Carpenter <dan.carpenter@oracle.com> wrote:
    > On Sun, Feb 26, 2012 at 07:03:30PM +0530, santosh nayak wrote:
    >> From: Santosh Nayak <santoshprasadnayak@gmail.com>
    >>
    >> Static checker is giving following warning:
    >> " error: calling 'spin_unlock_irqrestore()' with bogus flags"
    >>
    >> The code flow is as shown below:
    >> process_oq() --> process_one_iomb --> mpi_sata_completion
    >>
    >> In 'mpi_sata_completion'
    >> the first call for 'spin_unlock_irqrestore()' is with flags=0,
    >> which is as good as 'spin_unlock_irq()' ( unconditional interrupt
    >> enabling).
    >>
    >> So for better performance 'spin_unlock_irqrestore()' can be replaced
    >> with 'spin_unlock_irq()' and 'spin_lock_irqsave()' can be replaced by
    >> 'spin_lock_irq()'.
    >>
    >
    > process_oq() is called from the interrupt handler pm8001_chip_isr()
    > with interrupts disabled.
    >
    > drivers/scsi/pm8001/pm8001_hwi.c
    >  4301          spin_lock_irqsave(&pm8001_ha->lock, flags);
    >  4302          pm8001_chip_interrupt_disable(pm8001_ha);
    >  4303          process_oq(pm8001_ha);
    >  4304          pm8001_chip_interrupt_enable(pm8001_ha);
    >  4305          spin_unlock_irqrestore(&pm8001_ha->lock, flags);
    >
    > Probably we should just be doing a spin_lock() and spin_unlock()
    > without re-enabling the IRQs.  Should we even be doing that in the
    > irq handler anyway?
    >
    > regards,
    > dan carpenter
    >
    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2012-02-27 06:01    [W:0.070 / U:2.156 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site