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Blame 0032-virtiofsd-Poll-kick_fd-for-queue.patch

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From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
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Date: Mon, 27 Jan 2020 19:01:01 +0000
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Subject: [PATCH] virtiofsd: Poll kick_fd for queue
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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In the queue thread poll the kick_fd we're passed.
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Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
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Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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(cherry picked from commit 5dcd1f56141378226d33dc3df68ec57913e0aa04)
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---
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 tools/virtiofsd/fuse_virtio.c | 40 ++++++++++++++++++++++++++++++++++-
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 1 file changed, 39 insertions(+), 1 deletion(-)
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diff --git a/tools/virtiofsd/fuse_virtio.c b/tools/virtiofsd/fuse_virtio.c
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index 2a94bb3cca..05e7258712 100644
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--- a/tools/virtiofsd/fuse_virtio.c
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+++ b/tools/virtiofsd/fuse_virtio.c
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@@ -24,6 +24,7 @@
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 #include <stdio.h>
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 #include <stdlib.h>
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 #include <string.h>
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+#include <sys/eventfd.h>
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 #include <sys/socket.h>
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 #include <sys/types.h>
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 #include <sys/un.h>
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@@ -100,13 +101,50 @@ static void fv_panic(VuDev *dev, const char *err)
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     exit(EXIT_FAILURE);
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 }
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+/* Thread function for individual queues, created when a queue is 'started' */
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 static void *fv_queue_thread(void *opaque)
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 {
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     struct fv_QueueInfo *qi = opaque;
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     fuse_log(FUSE_LOG_INFO, "%s: Start for queue %d kick_fd %d\n", __func__,
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              qi->qidx, qi->kick_fd);
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     while (1) {
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-        /* TODO */
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+        struct pollfd pf[1];
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+        pf[0].fd = qi->kick_fd;
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+        pf[0].events = POLLIN;
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+        pf[0].revents = 0;
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+
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+        fuse_log(FUSE_LOG_DEBUG, "%s: Waiting for Queue %d event\n", __func__,
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+                 qi->qidx);
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+        int poll_res = ppoll(pf, 1, NULL, NULL);
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+
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+        if (poll_res == -1) {
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+            if (errno == EINTR) {
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+                fuse_log(FUSE_LOG_INFO, "%s: ppoll interrupted, going around\n",
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+                         __func__);
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+                continue;
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+            }
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+            fuse_log(FUSE_LOG_ERR, "fv_queue_thread ppoll: %m\n");
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+            break;
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+        }
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+        assert(poll_res == 1);
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+        if (pf[0].revents & (POLLERR | POLLHUP | POLLNVAL)) {
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+            fuse_log(FUSE_LOG_ERR, "%s: Unexpected poll revents %x Queue %d\n",
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+                     __func__, pf[0].revents, qi->qidx);
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+            break;
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+        }
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+        assert(pf[0].revents & POLLIN);
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+        fuse_log(FUSE_LOG_DEBUG, "%s: Got queue event on Queue %d\n", __func__,
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+                 qi->qidx);
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+
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+        eventfd_t evalue;
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+        if (eventfd_read(qi->kick_fd, &evalue)) {
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+            fuse_log(FUSE_LOG_ERR, "Eventfd_read for queue: %m\n");
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+            break;
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+        }
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+        if (qi->virtio_dev->se->debug) {
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+            fprintf(stderr, "%s: Queue %d gave evalue: %zx\n", __func__,
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+                    qi->qidx, (size_t)evalue);
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+        }
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     }
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     return NULL;