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[PULL 11/13] coroutine-ucontext: use QEMU_DEFINE_STATIC_CO_TLS()
From: |
Kevin Wolf |
Subject: |
[PULL 11/13] coroutine-ucontext: use QEMU_DEFINE_STATIC_CO_TLS() |
Date: |
Wed, 4 May 2022 16:25:20 +0200 |
From: Stefan Hajnoczi <stefanha@redhat.com>
Thread-Local Storage variables cannot be used directly from coroutine
code because the compiler may optimize TLS variable accesses across
qemu_coroutine_yield() calls. When the coroutine is re-entered from
another thread the TLS variables from the old thread must no longer be
used.
Use QEMU_DEFINE_STATIC_CO_TLS() for the current and leader variables.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20220307153853.602859-2-stefanha@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
util/coroutine-ucontext.c | 38 ++++++++++++++++++++++++--------------
1 file changed, 24 insertions(+), 14 deletions(-)
diff --git a/util/coroutine-ucontext.c b/util/coroutine-ucontext.c
index ed368e1a3e..ddc98fb4f8 100644
--- a/util/coroutine-ucontext.c
+++ b/util/coroutine-ucontext.c
@@ -25,6 +25,7 @@
#include "qemu/osdep.h"
#include <ucontext.h>
#include "qemu/coroutine_int.h"
+#include "qemu/coroutine-tls.h"
#ifdef CONFIG_VALGRIND_H
#include <valgrind/valgrind.h>
@@ -66,8 +67,8 @@ typedef struct {
/**
* Per-thread coroutine bookkeeping
*/
-static __thread CoroutineUContext leader;
-static __thread Coroutine *current;
+QEMU_DEFINE_STATIC_CO_TLS(Coroutine *, current);
+QEMU_DEFINE_STATIC_CO_TLS(CoroutineUContext, leader);
/*
* va_args to makecontext() must be type 'int', so passing
@@ -97,14 +98,15 @@ static inline __attribute__((always_inline))
void finish_switch_fiber(void *fake_stack_save)
{
#ifdef CONFIG_ASAN
+ CoroutineUContext *leaderp = get_ptr_leader();
const void *bottom_old;
size_t size_old;
__sanitizer_finish_switch_fiber(fake_stack_save, &bottom_old, &size_old);
- if (!leader.stack) {
- leader.stack = (void *)bottom_old;
- leader.stack_size = size_old;
+ if (!leaderp->stack) {
+ leaderp->stack = (void *)bottom_old;
+ leaderp->stack_size = size_old;
}
#endif
#ifdef CONFIG_TSAN
@@ -161,8 +163,10 @@ static void coroutine_trampoline(int i0, int i1)
/* Initialize longjmp environment and switch back the caller */
if (!sigsetjmp(self->env, 0)) {
- start_switch_fiber_asan(COROUTINE_YIELD, &fake_stack_save,
leader.stack,
- leader.stack_size);
+ CoroutineUContext *leaderp = get_ptr_leader();
+
+ start_switch_fiber_asan(COROUTINE_YIELD, &fake_stack_save,
+ leaderp->stack, leaderp->stack_size);
start_switch_fiber_tsan(&fake_stack_save, self, true); /* true=caller
*/
siglongjmp(*(sigjmp_buf *)co->entry_arg, 1);
}
@@ -297,7 +301,7 @@ qemu_coroutine_switch(Coroutine *from_, Coroutine *to_,
int ret;
void *fake_stack_save = NULL;
- current = to_;
+ set_current(to_);
ret = sigsetjmp(from->env, 0);
if (ret == 0) {
@@ -315,18 +319,24 @@ qemu_coroutine_switch(Coroutine *from_, Coroutine *to_,
Coroutine *qemu_coroutine_self(void)
{
- if (!current) {
- current = &leader.base;
+ Coroutine *self = get_current();
+ CoroutineUContext *leaderp = get_ptr_leader();
+
+ if (!self) {
+ self = &leaderp->base;
+ set_current(self);
}
#ifdef CONFIG_TSAN
- if (!leader.tsan_co_fiber) {
- leader.tsan_co_fiber = __tsan_get_current_fiber();
+ if (!leaderp->tsan_co_fiber) {
+ leaderp->tsan_co_fiber = __tsan_get_current_fiber();
}
#endif
- return current;
+ return self;
}
bool qemu_in_coroutine(void)
{
- return current && current->caller;
+ Coroutine *self = get_current();
+
+ return self && self->caller;
}
--
2.35.1
- [PULL 00/13] Block layer patches, Kevin Wolf, 2022/05/04
- [PULL 03/13] libvhost-user: Fix extra vu_add/rem_mem_reg reply, Kevin Wolf, 2022/05/04
- [PULL 07/13] Revert "main-loop: Disable GLOBAL_STATE_CODE() assertions", Kevin Wolf, 2022/05/04
- [PULL 04/13] vhost-user: Don't pass file descriptor for VHOST_USER_REM_MEM_REG, Kevin Wolf, 2022/05/04
- [PULL 02/13] docs/vhost-user: Clarifications for VHOST_USER_ADD/REM_MEM_REG, Kevin Wolf, 2022/05/04
- [PULL 05/13] block: Classify bdrv_get_flags() as I/O function, Kevin Wolf, 2022/05/04
- [PULL 01/13] qemu-img: properly list formats which have consistency check implemented, Kevin Wolf, 2022/05/04
- [PULL 06/13] qcow2: Do not reopen data_file in invalidate_cache, Kevin Wolf, 2022/05/04
- [PULL 10/13] iotests/reopen-file: Test reopening file child, Kevin Wolf, 2022/05/04
- [PULL 09/13] block/vmdk: Fix reopening bs->file, Kevin Wolf, 2022/05/04
- [PULL 11/13] coroutine-ucontext: use QEMU_DEFINE_STATIC_CO_TLS(),
Kevin Wolf <=
- [PULL 13/13] coroutine-win32: use QEMU_DEFINE_STATIC_CO_TLS(), Kevin Wolf, 2022/05/04
- [PULL 08/13] iotests: Add regression test for issue 945, Kevin Wolf, 2022/05/04
- [PULL 12/13] coroutine: use QEMU_DEFINE_STATIC_CO_TLS(), Kevin Wolf, 2022/05/04
- Re: [PULL 00/13] Block layer patches, Richard Henderson, 2022/05/05