From e6910a6739a73a60f3eedbc3765e75d6c2184796 Mon Sep 17 00:00:00 2001 Message-Id: In-Reply-To: <54163d537ed24926effb0783707492d2988ecbe8.1424280081.git.jen@redhat.com> References: <54163d537ed24926effb0783707492d2988ecbe8.1424280081.git.jen@redhat.com> From: Stefan Hajnoczi Date: Thu, 12 Feb 2015 14:16:21 -0500 Subject: [CHANGE 6/8] block: Repair the throttling code. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit To: rhvirt-patches@redhat.com, jen@redhat.com RH-Author: Stefan Hajnoczi Message-id: <1423750582-32065-4-git-send-email-stefanha@redhat.com> Patchwork-id: 63803 O-Subject: [RHEL-6.7 qemu-kvm PATCH 3/4] block: Repair the throttling code. Bugzilla: 1132848 RH-Acked-by: Fam Zheng RH-Acked-by: Paolo Bonzini RH-Acked-by: Max Reitz From: Benoît Canet The throttling code was segfaulting since commit 02ffb504485f0920cfc75a0982a602f824a9a4f4 because some qemu_co_queue_next caller does not run in a coroutine. qemu_co_queue_do_restart assume that the caller is a coroutinne. As suggested by Stefan fix this by entering the coroutine directly. Also make sure like suggested that qemu_co_queue_next() and qemu_co_queue_restart_all() can be called only in coroutines. Signed-off-by: Benoit Canet Signed-off-by: Stefan Hajnoczi (cherry picked from commit b681a1c73e15e08c70c10cccd9c9f5b65cca12e8) Signed-off-by: Stefan Hajnoczi The bug that this patch fixes is not present in RHEL6 because CoQueue is implemented using QEMUBH and 02ffb504485f0920cfc75a0982a602f824a9a4f4 has not been backported. The patch is still needed for two reasons: 1. To reduce block.c conflicts later since qemu_co_queue_next() is replaced with qemu_co_enter_next(). 2. To add the qemu_co_enter_next() function used by the new I/O throttling implementation. Signed-off-by: Jeff E. Nelson Conflicts: include/block/coroutine.h The path is ./qemu-coroutine.h in RHEL6. qemu-coroutine-lock.c Drop coroutine_fn and assert(qemu_in_coroutine()) since RHEL6 CoQueue does not suffer from the bug that this patch fixed upstream. It's perfectly fine to call qemu_co_queue_next() and qemu_co_queue_restart_all() outside coroutine context in RHEL6. --- block.c | 7 +++---- qemu-coroutine-lock.c | 14 ++++++++++++++ qemu-coroutine.h | 5 +++++ 3 files changed, 22 insertions(+), 4 deletions(-) Signed-off-by: Jeff E. Nelson --- block.c | 7 +++---- qemu-coroutine-lock.c | 14 ++++++++++++++ qemu-coroutine.h | 5 +++++ 3 files changed, 22 insertions(+), 4 deletions(-) diff --git a/block.c b/block.c index 29bab36..e3662ff 100644 --- a/block.c +++ b/block.c @@ -125,7 +125,7 @@ void bdrv_io_limits_disable(BlockDriverState *bs) { bs->io_limits_enabled = false; - while (qemu_co_queue_next(&bs->throttled_reqs)); + do {} while (qemu_co_enter_next(&bs->throttled_reqs)); if (bs->block_timer) { qemu_del_timer(bs->block_timer); @@ -141,7 +141,7 @@ static void bdrv_block_timer(void *opaque) { BlockDriverState *bs = opaque; - qemu_co_queue_next(&bs->throttled_reqs); + qemu_co_enter_next(&bs->throttled_reqs); } void bdrv_io_limits_enable(BlockDriverState *bs) @@ -1135,8 +1135,7 @@ void bdrv_drain_all(void) * a busy wait. */ QTAILQ_FOREACH(bs, &bdrv_states, list) { - if (!qemu_co_queue_empty(&bs->throttled_reqs)) { - qemu_co_queue_restart_all(&bs->throttled_reqs); + while (qemu_co_enter_next(&bs->throttled_reqs)) { busy = true; } } diff --git a/qemu-coroutine-lock.c b/qemu-coroutine-lock.c index 85d3cc4..84c8a07 100644 --- a/qemu-coroutine-lock.c +++ b/qemu-coroutine-lock.c @@ -90,6 +90,20 @@ void qemu_co_queue_restart_all(CoQueue *queue) } } +bool qemu_co_enter_next(CoQueue *queue) +{ + Coroutine *next; + + next = QTAILQ_FIRST(&queue->entries); + if (!next) { + return false; + } + + QTAILQ_REMOVE(&queue->entries, next, co_queue_next); + qemu_coroutine_enter(next, NULL); + return true; +} + bool qemu_co_queue_empty(CoQueue *queue) { return (QTAILQ_FIRST(&queue->entries) == NULL); diff --git a/qemu-coroutine.h b/qemu-coroutine.h index b1c21d9..4e71404 100644 --- a/qemu-coroutine.h +++ b/qemu-coroutine.h @@ -137,6 +137,11 @@ bool qemu_co_queue_next(CoQueue *queue); void qemu_co_queue_restart_all(CoQueue *queue); /** + * Enter the next coroutine in the queue + */ +bool qemu_co_enter_next(CoQueue *queue); + +/** * Checks if the CoQueue is empty. */ bool qemu_co_queue_empty(CoQueue *queue); -- 2.1.0