On 05-07-2022 21:02, Saurabh Sengar wrote:
> There can be scenarios where packets in ring buffer are continuously
> getting queued from upper layer and dequeued from storvsc interrupt
> handler, such scenarios can hold the foreach_vmbus_pkt loop (which is
> executing as a tasklet) for a long duration. Theoretically its possible
> that this loop executes forever. Add a condition to limit execution of
> this tasklet for finite amount of time to avoid such hazardous scenarios.
>
> Signed-off-by: Saurabh Sengar <ssengar@xxxxxxxxxxxxxxxxxxx>
> ---
> drivers/scsi/storvsc_drv.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
> index fe000da..0c428cb 100644
> --- a/drivers/scsi/storvsc_drv.c
> +++ b/drivers/scsi/storvsc_drv.c
> @@ -60,6 +60,9 @@
> #define VMSTOR_PROTO_VERSION_WIN8_1 VMSTOR_PROTO_VERSION(6, 0)
> #define VMSTOR_PROTO_VERSION_WIN10 VMSTOR_PROTO_VERSION(6, 2)
>
> +/* channel callback timeout in ms */
> +#define CALLBACK_TIMEOUT 5
If I may, it would be good if we have the CALLBACK_TIMEOUT configurable based upon user's requirement with default value to '5'.
I assume, this value '5' fits best to the use-case which we are trying to resolve here. Thanks.
> +
> /* Packet structure describing virtual storage requests. */
> enum vstor_packet_operation {
> VSTOR_OPERATION_COMPLETE_IO = 1,
> @@ -1204,6 +1207,7 @@ static void storvsc_on_channel_callback(void *context)
> struct hv_device *device;
> struct storvsc_device *stor_device;
> struct Scsi_Host *shost;
> + unsigned long expire = jiffies + msecs_to_jiffies(CALLBACK_TIMEOUT);
>
> if (channel->primary_channel != NULL)
> device = channel->primary_channel->device_obj;
> @@ -1224,6 +1228,9 @@ static void storvsc_on_channel_callback(void *context)
> u32 minlen = rqst_id ? sizeof(struct vstor_packet) :
> sizeof(enum vstor_packet_operation);
>
> + if (time_after(jiffies, expire))
> + break;
> +
> if (pktlen < minlen) {
> dev_err(&device->device,
> "Invalid pkt: id=%llu, len=%u, minlen=%u\n",
Regards,
~Praveen.
