On Tue, Apr 17, 2012 at 11:25:04AM +0530, nagalakshmi.nandigama@xxxxxxx wrote:
> When CONFIG_DEBUG_PREEMPT is enabled, bug is observed in the smp_processor_id().
> This is because smp_processor_id() is not called in preempt safe condition.
>
> To fix this issue, use raw_smp_processor_id instead of smp_processor_id.
Just so we're clear, "fix this issue" really means "paper over the warning".
* NOTE: raw_smp_processor_id() is for internal use only
* (smp_processor_id() is the preferred variant), but in rare
* instances it might also be used to turn off false positives
* (i.e. smp_processor_id() use that the debugging code reports but
* which use for some reason is legal). Don't use this to hack around
* the warning message, as your code might not work under PREEMPT.
As far as I can tell, it's called under a lock already so should be
non-preemptable ... can you share the backtrace you get?
> Signed-off-by: Nagalakshmi Nandigama <nagalakshmi.nandigama@xxxxxxx>
> CC: stable@xxxxxxxxxxxxxxx
> ---
>
> diff --git a/drivers/scsi/mpt2sas/mpt2sas_base.c b/drivers/scsi/mpt2sas/mpt2sas_base.c
> index 272fab7..b010be0 100644
> --- a/drivers/scsi/mpt2sas/mpt2sas_base.c
> +++ b/drivers/scsi/mpt2sas/mpt2sas_base.c
> @@ -1792,7 +1792,7 @@ static inline void _base_writeq(__u64 b, volatile void __iomem *addr,
> static inline u8
> _base_get_msix_index(struct MPT2SAS_ADAPTER *ioc)
> {
> - return ioc->cpu_msix_table[smp_processor_id()];
> + return ioc->cpu_msix_table[raw_smp_processor_id()];
> }
>
> /**
> --
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