On 01/09/2019 08:58 PM, Tyrel Datwyler wrote:
> While mapping DMA for scatter list when a scsi command is queued the
> existing call to dma_alloc_coherent() in our map_sg_data() function
> passes zero for the gfp_flags parameter. We are most definitly in atomic
> context at this point as queue_command() is called in softirq context
> and further we have a spinlock holding the scsi host lock.
>
> Fix this by passing GFP_ATOMIC to dma_alloc_coherent() to prevent any
> sort of sleeping in atomic context deadlock.
>
> Fixes: 4dddbc26c389 ("[SCSI] ibmvscsi: handle large scatter/gather lists")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Tyrel Datwyler <tyreld@xxxxxxxxxxxxxxxxxx>
> ---
> drivers/scsi/ibmvscsi/ibmvscsi.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.c b/drivers/scsi/ibmvscsi/ibmvscsi.c
> index 1135e74..cb8535e 100644
> --- a/drivers/scsi/ibmvscsi/ibmvscsi.c
> +++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
> @@ -731,7 +731,7 @@ static int map_sg_data(struct scsi_cmnd *cmd,
> evt_struct->ext_list = (struct srp_direct_buf *)
> dma_alloc_coherent(dev,
> SG_ALL * sizeof(struct srp_direct_buf),
> - &evt_struct->ext_list_token, 0);
> + &evt_struct->ext_list_token, GFP_ATOMIC);
> if (!evt_struct->ext_list) {
> if (!firmware_has_feature(FW_FEATURE_CMO))
> sdev_printk(KERN_ERR, cmd->device,
>
Reviewed-by: Brian King <brking@xxxxxxxxxxxxxxxxxx>
--
Brian King
Power Linux I/O
IBM Linux Technology Center
