Re: [PATCH] megaraid: Fix a sleep-in-atomic bug

[Jia-Ju Bai]

On 05/31/2017 06:18 PM, Sumit Saxena wrote:
> > -----Original Message-----
> > From: Jia-Ju Bai [mailto:baijiaju1990@xxxxxxx]
> > Sent: Wednesday, May 31, 2017 8:27 AM
> > To: kashyap.desai@xxxxxxxxxxxx; sumit.saxena@xxxxxxxxxxxx;
> > shivasharan.srikanteshwara@xxxxxxxxxxxx; jejb@xxxxxxxxxxxxxxxxxx;
> > martin.petersen@xxxxxxxxxx
> > Cc: megaraidlinux.pdl@xxxxxxxxxxxx; linux-scsi@xxxxxxxxxxxxxxx; linux-
> > kernel@xxxxxxxxxxxxxxx; Jia-Ju Bai
> > Subject: [PATCH] megaraid: Fix a sleep-in-atomic bug
> >
> > The driver may sleep under a spin lock, and the function call path is:
> > mraid_mm_attach_buf (acquire the lock by spin_lock_irqsave)
> >   pci_pool_alloc(GFP_KERNEL) -->  may sleep
> >
> > To fix it, the "GFP_KERNEL" is replaced with "GFP_ATOMIC".
> >
> > Signed-off-by: Jia-Ju Bai<baijiaju1990@xxxxxxx>
> > ---
> > drivers/scsi/megaraid/megaraid_mm.c |    2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/scsi/megaraid/megaraid_mm.c
> > b/drivers/scsi/megaraid/megaraid_mm.c
> > index 4cf9ed9..c43afb8 100644
> > --- a/drivers/scsi/megaraid/megaraid_mm.c
> > +++ b/drivers/scsi/megaraid/megaraid_mm.c
> > @@ -574,7 +574,7 @@
> >
> > 	kioc->pool_index	= right_pool;
> > 	kioc->free_buf		= 1;
> > -	kioc->buf_vaddr 	= pci_pool_alloc(pool->handle, GFP_KERNEL,
> > +	kioc->buf_vaddr 	= pci_pool_alloc(pool->handle, GFP_ATOMIC,
> > 							&kioc->buf_paddr);
> > 	spin_unlock_irqrestore(&pool->lock, flags);
> This is very old driver and reached EOL. Did you face any issue because of
> this bug or discover this through code review?
> Anyways patch looks good to me.
>
> Acked-by: Sumit Saxena<sumit.saxena@xxxxxxxxxxxx>
>
> > --
> > 1.7.9.5
Hi,

This bug is found by a static analysis tool and my code review.

Jia-Ju Bai