From: Sergey Fedorov <serge.f...@gmail.com>
The check is to make sure that another thread hasn't already done the
same while we were outside of tb_lock. Mention this in a comment.
Signed-off-by: Sergey Fedorov <serge.f...@gmail.com>
Signed-off-by: Sergey Fedorov <sergey.fedo...@linaro.org>
---
Changes in v2:
* Typo fixed in the commit title
* Complete rewrite of the commit body and the patch based on Paolo's comments
include/exec/exec-all.h | 31 +++++++++++++++++--------------
1 file changed, 17 insertions(+), 14 deletions(-)
diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h
index b055716ed690..8e81ef5fb2c2 100644
--- a/include/exec/exec-all.h
+++ b/include/exec/exec-all.h
@@ -391,21 +391,24 @@ static inline void tb_set_jmp_target(TranslationBlock *tb,
static inline void tb_add_jump(TranslationBlock *tb, int n,
TranslationBlock *tb_next)
{
- /* NOTE: this test is only needed for thread safety */
- if (!tb->jmp_list_next[n]) {
- qemu_log_mask_and_addr(CPU_LOG_EXEC, tb->pc,
- "Linking TBs %p [" TARGET_FMT_lx
- "] index %d -> %p [" TARGET_FMT_lx "]\n",
- tb->tc_ptr, tb->pc, n,
- tb_next->tc_ptr, tb_next->pc);
- /* patch the native jump address */
- tb_set_jmp_target(tb, n, (uintptr_t)tb_next->tc_ptr);
-
- /* add in TB jmp circular list */
- tb->jmp_list_next[n] = tb_next->jmp_list_first;
- assert(((uintptr_t)tb & 3) == 0);
- tb_next->jmp_list_first = (uintptr_t)tb | n;
+ if (tb->jmp_list_next[n]) {
+ /* Another thread has already done this while we were
+ * outside of the lock; nothing to do in this case */
+ return;
}
+ qemu_log_mask_and_addr(CPU_LOG_EXEC, tb->pc,
+ "Linking TBs %p [" TARGET_FMT_lx
+ "] index %d -> %p [" TARGET_FMT_lx "]\n",
+ tb->tc_ptr, tb->pc, n,
+ tb_next->tc_ptr, tb_next->pc);
+
+ /* patch the native jump address */
+ tb_set_jmp_target(tb, n, (uintptr_t)tb_next->tc_ptr);
+
+ /* add in TB jmp circular list */
+ tb->jmp_list_next[n] = tb_next->jmp_list_first;
+ assert(((uintptr_t)tb & 3) == 0);
+ tb_next->jmp_list_first = (uintptr_t)tb | n;
}
/* GETRA is the true target of the return instruction that we'll execute,
--
2.8.1
