[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] [PATCH] XenBus: Don't wait for producer to fill the ring if the ring

On 17/05/2017 16:56, Jan Beulich wrote:
On 17.05.17 at 16:57, <anshul.makkar@xxxxxxxxxx> wrote:
The condition to check for if there is space in the ring buffer
    also becomes true if the buffer is full, thus consumer waits for
    the producer to fill the buffer eventhough it is already full.

    To resolve the situation, check if the buffer is full and then
    break from the loop.
    e.g case: prod = 1272, cons = 248.

    Signed-off-by: Anshul Makkar <anshul.makkar@xxxxxxxxxx>

Please avoid indenting the entire commit message.
Oh. sorry about that. I saw this format in few previous commits and adopted it. Will correct it.

--- a/tools/firmware/hvmloader/xenbus.c
+++ b/tools/firmware/hvmloader/xenbus.c
@@ -141,7 +141,18 @@ static void ring_read(char *data, uint32_t len)
         /* Don't overrun the producer pointer */
         while ( (part = MASK_XENSTORE_IDX(rings->rsp_prod -
                                           rings->rsp_cons)) == 0 )
+        {
+            /* don't wait for producer to fill the ring if it is already full.
+             * Condition happens when you write string > 1K into the ring.
+             * eg case prod=1272 cons=248.
+             */

Comment style.

+            if ( !(XENSTORE_RING_SIZE - (rings->rsp_prod - rings->rsp_cons)) )

Is this any different from

           if ( rings->rsp_prod - rings->rsp_cons == XENSTORE_RING_SIZE  )
No, its same. Ok, will use the suggested approach.



Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.