From 0493fc983cc97eeb9c142ab7efcfce940f0cf75d Mon Sep 17 00:00:00 2001

From: Paolo Bonzini <pbonzini@redhat.com>

Date: Wed, 17 May 2017 13:09:21 +0200

Subject: [PATCH 15/27] curl: do not do aio_poll when waiting for a free

 CURLState

RH-Author: Paolo Bonzini <pbonzini@redhat.com>

Message-id: <20170517130921.27402-8-pbonzini@redhat.com>

Patchwork-id: 75266

O-Subject: [RHEL7.4 qemu-kvm PATCH v2 7/7] curl: do not do aio_poll when waiting for a free CURLState

Bugzilla: 1437393

RH-Acked-by: Max Reitz <mreitz@redhat.com>

RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

RH-Acked-by: Jeffrey Cody <jcody@redhat.com>

Instead, put the CURLAIOCB on a wait list and yield; curl_clean_state will

wake the corresponding coroutine.

Because of CURL's callback-based structure, we cannot easily convert

everything to CoMutex/CoQueue; keeping the QemuMutex is simpler.  However,

CoQueue is a simple wrapper around a linked list, so we can easily

use QSIMPLEQ and open-code a CoQueue, protected by the BDRVCURLState

QemuMutex instead of a CoMutex.

Reviewed-by: Jeff Cody <jcody@redhat.com>

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Reviewed-by: Max Reitz <mreitz@redhat.com>

Message-id: 20170515100059.15795-8-pbonzini@redhat.com

Signed-off-by: Jeff Cody <jcody@redhat.com>

(cherry picked from commit 2bb5c936c5827e1d831002f7a7517cb8c2c2201d)

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 block/curl.c | 16 +++++++++++++++-

 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/block/curl.c b/block/curl.c

index acfbe52..eb9fda7 100644

--- a/block/curl.c

+++ b/block/curl.c

@@ -98,6 +98,8 @@ typedef struct CURLAIOCB {

     size_t start;

     size_t end;

+

+    QSIMPLEQ_ENTRY(CURLAIOCB) next;

 } CURLAIOCB;

 typedef struct CURLSocket {

@@ -133,6 +135,7 @@ typedef struct BDRVCURLState {

     bool accept_range;

     AioContext *aio_context;

     QemuMutex mutex;

+    QSIMPLEQ_HEAD(, CURLAIOCB) free_state_waitq;

     char *username;

     char *password;

     char *proxyusername;

@@ -532,6 +535,7 @@ static int curl_init_state(BDRVCURLState *s, CURLState *state)

 /* Called with s->mutex held.  */

 static void curl_clean_state(CURLState *s)

 {

+    CURLAIOCB *next;

     int j;

     for (j = 0; j < CURL_NUM_ACB; j++) {

         assert(!s->acb[j]);

@@ -548,6 +552,14 @@ static void curl_clean_state(CURLState *s)

     }

     s->in_use = 0;

+

+    next = QSIMPLEQ_FIRST(&s->s->free_state_waitq);

+    if (next) {

+        QSIMPLEQ_REMOVE_HEAD(&s->s->free_state_waitq, next);

+        qemu_mutex_unlock(&s->s->mutex);

+        aio_co_wake(next->co);

+        qemu_mutex_lock(&s->s->mutex);

+    }

 }

 static void curl_parse_filename(const char *filename, QDict *options,

@@ -744,6 +756,7 @@ static int curl_open(BlockDriverState *bs, QDict *options, int flags,

     }

     DPRINTF("CURL: Opening %s\n", file);

+    QSIMPLEQ_INIT(&s->free_state_waitq);

     s->aio_context = bdrv_get_aio_context(bs);

     s->url = g_strdup(file);

     qemu_mutex_lock(&s->mutex);

@@ -844,8 +857,9 @@ static void curl_setup_preadv(BlockDriverState *bs, CURLAIOCB *acb)

         if (state) {

             break;

         }

+        QSIMPLEQ_INSERT_TAIL(&s->free_state_waitq, acb, next);

         qemu_mutex_unlock(&s->mutex);

-        aio_poll(bdrv_get_aio_context(bs), true);

+        qemu_coroutine_yield();

         qemu_mutex_lock(&s->mutex);

     }

-- 

1.8.3.1