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

[Jia-Ju Bai <baijiaju1990@163.com>]

On 05/31/2017 06:18 PM, Sumit Saxena wrote:
>> -----Original Message-----
>> From: Jia-Ju Bai [mailto:baijiaju1990@163.com]
>> Sent: Wednesday, May 31, 2017 8:27 AM
>> To: kashyap.desai@broadcom.com; sumit.saxena@broadcom.com;
>> shivasharan.srikanteshwara@broadcom.com; jejb@linux.vnet.ibm.com;
>> martin.petersen@oracle.com
>> Cc: megaraidlinux.pdl@broadcom.com; linux-scsi@vger.kernel.org; linux-
>> kernel@vger.kernel.org; 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@163.com>
>> ---
>> 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@broadcom.com>
>
>> --
>> 1.7.9.5
>>
Hi,

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

Jia-Ju Bai