140 lines
5.6 KiB
Diff
140 lines
5.6 KiB
Diff
From 9c2e55d25fec6ffb21e344513b7dbeed7e21f641 Mon Sep 17 00:00:00 2001
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From: Stefan Hajnoczi <stefanha@redhat.com>
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Date: Tue, 17 May 2022 12:08:04 +0100
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Subject: [PATCH 2/6] coroutine: use QEMU_DEFINE_STATIC_CO_TLS()
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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: Stefan Hajnoczi <stefanha@redhat.com>
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RH-MergeRequest: 89: coroutine: use coroutine TLS macros to protect thread-local variables
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RH-Commit: [2/3] 68a8847e406e2eace6ddc31b0c5676a60600d606 (stefanha/centos-stream-qemu-kvm)
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RH-Bugzilla: 1952483
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RH-Acked-by: Hanna Reitz <hreitz@redhat.com>
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RH-Acked-by: Eric Blake <eblake@redhat.com>
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RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
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Thread-Local Storage variables cannot be used directly from coroutine
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code because the compiler may optimize TLS variable accesses across
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qemu_coroutine_yield() calls. When the coroutine is re-entered from
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another thread the TLS variables from the old thread must no longer be
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used.
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Use QEMU_DEFINE_STATIC_CO_TLS() for the current and leader variables.
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The alloc_pool QSLIST needs a typedef so the return value of
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get_ptr_alloc_pool() can be stored in a local variable.
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One example of why this code is necessary: a coroutine that yields
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before calling qemu_coroutine_create() to create another coroutine is
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affected by the TLS issue.
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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Message-Id: <20220307153853.602859-3-stefanha@redhat.com>
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Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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(cherry picked from commit ac387a08a9c9f6b36757da912f0339c25f421f90)
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Conflicts:
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- Context conflicts due to commit 5411171c3ef4 ("coroutine: Revert to
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constant batch size").
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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---
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util/qemu-coroutine.c | 41 ++++++++++++++++++++++++-----------------
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1 file changed, 24 insertions(+), 17 deletions(-)
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diff --git a/util/qemu-coroutine.c b/util/qemu-coroutine.c
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index 804f672e0a..4a8bd63ef0 100644
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--- a/util/qemu-coroutine.c
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+++ b/util/qemu-coroutine.c
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@@ -18,6 +18,7 @@
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#include "qemu/atomic.h"
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#include "qemu/coroutine.h"
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#include "qemu/coroutine_int.h"
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+#include "qemu/coroutine-tls.h"
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#include "block/aio.h"
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/**
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@@ -35,17 +36,20 @@ enum {
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static QSLIST_HEAD(, Coroutine) release_pool = QSLIST_HEAD_INITIALIZER(pool);
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static unsigned int pool_max_size = POOL_INITIAL_MAX_SIZE;
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static unsigned int release_pool_size;
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-static __thread QSLIST_HEAD(, Coroutine) alloc_pool = QSLIST_HEAD_INITIALIZER(pool);
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-static __thread unsigned int alloc_pool_size;
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-static __thread Notifier coroutine_pool_cleanup_notifier;
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+
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+typedef QSLIST_HEAD(, Coroutine) CoroutineQSList;
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+QEMU_DEFINE_STATIC_CO_TLS(CoroutineQSList, alloc_pool);
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+QEMU_DEFINE_STATIC_CO_TLS(unsigned int, alloc_pool_size);
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+QEMU_DEFINE_STATIC_CO_TLS(Notifier, coroutine_pool_cleanup_notifier);
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static void coroutine_pool_cleanup(Notifier *n, void *value)
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{
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Coroutine *co;
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Coroutine *tmp;
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+ CoroutineQSList *alloc_pool = get_ptr_alloc_pool();
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- QSLIST_FOREACH_SAFE(co, &alloc_pool, pool_next, tmp) {
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- QSLIST_REMOVE_HEAD(&alloc_pool, pool_next);
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+ QSLIST_FOREACH_SAFE(co, alloc_pool, pool_next, tmp) {
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+ QSLIST_REMOVE_HEAD(alloc_pool, pool_next);
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qemu_coroutine_delete(co);
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}
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}
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@@ -55,27 +59,30 @@ Coroutine *qemu_coroutine_create(CoroutineEntry *entry, void *opaque)
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Coroutine *co = NULL;
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if (CONFIG_COROUTINE_POOL) {
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- co = QSLIST_FIRST(&alloc_pool);
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+ CoroutineQSList *alloc_pool = get_ptr_alloc_pool();
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+
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+ co = QSLIST_FIRST(alloc_pool);
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if (!co) {
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if (release_pool_size > POOL_MIN_BATCH_SIZE) {
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/* Slow path; a good place to register the destructor, too. */
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- if (!coroutine_pool_cleanup_notifier.notify) {
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- coroutine_pool_cleanup_notifier.notify = coroutine_pool_cleanup;
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- qemu_thread_atexit_add(&coroutine_pool_cleanup_notifier);
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+ Notifier *notifier = get_ptr_coroutine_pool_cleanup_notifier();
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+ if (!notifier->notify) {
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+ notifier->notify = coroutine_pool_cleanup;
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+ qemu_thread_atexit_add(notifier);
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}
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/* This is not exact; there could be a little skew between
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* release_pool_size and the actual size of release_pool. But
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* it is just a heuristic, it does not need to be perfect.
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*/
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- alloc_pool_size = qatomic_xchg(&release_pool_size, 0);
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- QSLIST_MOVE_ATOMIC(&alloc_pool, &release_pool);
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- co = QSLIST_FIRST(&alloc_pool);
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+ set_alloc_pool_size(qatomic_xchg(&release_pool_size, 0));
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+ QSLIST_MOVE_ATOMIC(alloc_pool, &release_pool);
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+ co = QSLIST_FIRST(alloc_pool);
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}
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}
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if (co) {
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- QSLIST_REMOVE_HEAD(&alloc_pool, pool_next);
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- alloc_pool_size--;
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+ QSLIST_REMOVE_HEAD(alloc_pool, pool_next);
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+ set_alloc_pool_size(get_alloc_pool_size() - 1);
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}
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}
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@@ -99,9 +106,9 @@ static void coroutine_delete(Coroutine *co)
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qatomic_inc(&release_pool_size);
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return;
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}
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- if (alloc_pool_size < qatomic_read(&pool_max_size)) {
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- QSLIST_INSERT_HEAD(&alloc_pool, co, pool_next);
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- alloc_pool_size++;
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+ if (get_alloc_pool_size() < qatomic_read(&pool_max_size)) {
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+ QSLIST_INSERT_HEAD(get_ptr_alloc_pool(), co, pool_next);
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+ set_alloc_pool_size(get_alloc_pool_size() + 1);
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return;
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}
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}
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--
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2.31.1
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