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From b4af2eff8ecadb4e2c9520602455f77fac2cb943 Mon Sep 17 00:00:00 2001
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From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
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Date: Mon, 27 Jan 2020 19:01:02 +0100
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Subject: [PATCH 031/116] virtiofsd: Start reading commands from 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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RH-Author: Dr. David Alan Gilbert <dgilbert@redhat.com>
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Message-id: <20200127190227.40942-28-dgilbert@redhat.com>
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Patchwork-id: 93484
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O-Subject: [RHEL-AV-8.2 qemu-kvm PATCH 027/112] virtiofsd: Start reading commands from queue
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Bugzilla: 1694164
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RH-Acked-by: Philippe Mathieu-Daudé <philmd@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Sergio Lopez Pascual <slp@redhat.com>
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From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
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Pop queue elements off queues, copy the data from them and
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pass that to fuse.
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  Note: 'out' in a VuVirtqElement is from QEMU
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        'in' in libfuse is into the daemon
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  So we read from the out iov's to get a fuse_in_header
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When we get a kick we've got to read all the elements until the queue
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is empty.
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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 b509e1228b3e5eb83c14819045988999fc2dbd1b)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 tools/virtiofsd/fuse_i.h      |  2 +
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 tools/virtiofsd/fuse_virtio.c | 99 +++++++++++++++++++++++++++++++++++++++++--
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 2 files changed, 98 insertions(+), 3 deletions(-)
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diff --git a/tools/virtiofsd/fuse_i.h b/tools/virtiofsd/fuse_i.h
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index ec04449..1126723 100644
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--- a/tools/virtiofsd/fuse_i.h
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+++ b/tools/virtiofsd/fuse_i.h
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@@ -14,6 +14,7 @@
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 #include "fuse_lowlevel.h"
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 struct fv_VuDev;
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+struct fv_QueueInfo;
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 struct fuse_req {
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     struct fuse_session *se;
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@@ -75,6 +76,7 @@ struct fuse_chan {
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     pthread_mutex_t lock;
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     int ctr;
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     int fd;
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+    struct fv_QueueInfo *qi;
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 };
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 /**
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diff --git a/tools/virtiofsd/fuse_virtio.c b/tools/virtiofsd/fuse_virtio.c
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index 05e7258..3841b20 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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@@ -12,6 +12,7 @@
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  */
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 #include "qemu/osdep.h"
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+#include "qemu/iov.h"
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 #include "fuse_virtio.h"
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 #include "fuse_i.h"
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 #include "standard-headers/linux/fuse.h"
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@@ -32,6 +33,7 @@
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 #include "contrib/libvhost-user/libvhost-user.h"
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+struct fv_VuDev;
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 struct fv_QueueInfo {
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     pthread_t thread;
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     struct fv_VuDev *virtio_dev;
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@@ -101,10 +103,41 @@ static void fv_panic(VuDev *dev, const char *err)
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     exit(EXIT_FAILURE);
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 }
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+/*
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+ * Copy from an iovec into a fuse_buf (memory only)
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+ * Caller must ensure there is space
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+ */
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+static void copy_from_iov(struct fuse_buf *buf, size_t out_num,
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+                          const struct iovec *out_sg)
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+{
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+    void *dest = buf->mem;
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+
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+    while (out_num) {
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+        size_t onelen = out_sg->iov_len;
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+        memcpy(dest, out_sg->iov_base, onelen);
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+        dest += onelen;
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+        out_sg++;
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+        out_num--;
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+    }
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+}
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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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+    struct VuDev *dev = &qi->virtio_dev->dev;
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+    struct VuVirtq *q = vu_get_queue(dev, qi->qidx);
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+    struct fuse_session *se = qi->virtio_dev->se;
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+    struct fuse_chan ch;
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+    struct fuse_buf fbuf;
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+
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+    fbuf.mem = NULL;
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+    fbuf.flags = 0;
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+
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+    fuse_mutex_init(&ch.lock);
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+    ch.fd = (int)0xdaff0d111;
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+    ch.qi = qi;
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+
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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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@@ -141,11 +174,71 @@ static void *fv_queue_thread(void *opaque)
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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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+        /* out is from guest, in is too guest */
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+        unsigned int in_bytes, out_bytes;
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+        vu_queue_get_avail_bytes(dev, q, &in_bytes, &out_bytes, ~0, ~0);
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+
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+        fuse_log(FUSE_LOG_DEBUG,
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+                 "%s: Queue %d gave evalue: %zx available: in: %u out: %u\n",
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+                 __func__, qi->qidx, (size_t)evalue, in_bytes, out_bytes);
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+
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+        while (1) {
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+            /*
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+             * An element contains one request and the space to send our
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+             * response They're spread over multiple descriptors in a
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+             * scatter/gather set and we can't trust the guest to keep them
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+             * still; so copy in/out.
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+             */
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+            VuVirtqElement *elem = vu_queue_pop(dev, q, sizeof(VuVirtqElement));
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+            if (!elem) {
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+                break;
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+            }
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+
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+            if (!fbuf.mem) {
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+                fbuf.mem = malloc(se->bufsize);
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+                assert(fbuf.mem);
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+                assert(se->bufsize > sizeof(struct fuse_in_header));
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+            }
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+            /* The 'out' part of the elem is from qemu */
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+            unsigned int out_num = elem->out_num;
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+            struct iovec *out_sg = elem->out_sg;
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+            size_t out_len = iov_size(out_sg, out_num);
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+            fuse_log(FUSE_LOG_DEBUG,
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+                     "%s: elem %d: with %d out desc of length %zd\n", __func__,
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+                     elem->index, out_num, out_len);
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+
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+            /*
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+             * The elem should contain a 'fuse_in_header' (in to fuse)
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+             * plus the data based on the len in the header.
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+             */
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+            if (out_len < sizeof(struct fuse_in_header)) {
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+                fuse_log(FUSE_LOG_ERR, "%s: elem %d too short for in_header\n",
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+                         __func__, elem->index);
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+                assert(0); /* TODO */
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+            }
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+            if (out_len > se->bufsize) {
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+                fuse_log(FUSE_LOG_ERR, "%s: elem %d too large for buffer\n",
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+                         __func__, elem->index);
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+                assert(0); /* TODO */
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+            }
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+            copy_from_iov(&fbuf, out_num, out_sg);
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+            fbuf.size = out_len;
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+
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+            /* TODO! Endianness of header */
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+
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+            /* TODO: Fixup fuse_send_msg */
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+            /* TODO: Add checks for fuse_session_exited */
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+            fuse_session_process_buf_int(se, &fbuf, &ch);
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+
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+            /* TODO: vu_queue_push(dev, q, elem, qi->write_count); */
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+            vu_queue_notify(dev, q);
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+
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+            free(elem);
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+            elem = NULL;
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         }
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     }
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+    pthread_mutex_destroy(&ch.lock);
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+    free(fbuf.mem);
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     return NULL;
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 }
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-- 
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1.8.3.1
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