Sergey Fedorov <serge.f...@gmail.com> writes: > On 14/07/16 11:41, Alex Bennée wrote: >> Sergey Fedorov <sergey.fedo...@linaro.org> writes: >> >>> From: Sergey Fedorov <serge.f...@gmail.com> >>> >>> Use async_safe_run_on_cpu() to make tb_flush() thread safe. >>> >>> Signed-off-by: Sergey Fedorov <serge.f...@gmail.com> >>> Signed-off-by: Sergey Fedorov <sergey.fedo...@linaro.org> >>> --- >>> >>> Changes in v2: >>> - stale comment about unsafe tb_flush() removed >>> --- >>> translate-all.c | 13 ++++++++----- >>> 1 file changed, 8 insertions(+), 5 deletions(-) >>> >>> diff --git a/translate-all.c b/translate-all.c >>> index eaa95e4cd7dc..e69b5d4e889e 100644 >>> --- a/translate-all.c >>> +++ b/translate-all.c >>> @@ -831,8 +831,7 @@ static void page_flush_tb(void) >>> } >>> >>> /* flush all the translation blocks */ >>> -/* XXX: tb_flush is currently not thread safe */ >>> -void tb_flush(CPUState *cpu) >>> +static void do_tb_flush(CPUState *cpu, void *data) >>> { >>> #if defined(DEBUG_FLUSH) >>> printf("qemu: flush code_size=%ld nb_tbs=%d avg_tb_size=%ld\n", >>> @@ -861,6 +860,11 @@ void tb_flush(CPUState *cpu) >>> tcg_ctx.tb_ctx.tb_flush_count++; >>> } >>> >>> +void tb_flush(CPUState *cpu) >>> +{ >>> + async_safe_run_on_cpu(cpu, do_tb_flush, NULL); >>> +} >>> + >>> #ifdef DEBUG_TB_CHECK >>> >>> static void >>> @@ -1163,9 +1167,8 @@ TranslationBlock *tb_gen_code(CPUState *cpu, >>> buffer_overflow: >>> /* flush must be done */ >>> tb_flush(cpu); >>> - /* cannot fail at this point */ >>> - tb = tb_alloc(pc); >>> - assert(tb != NULL); >>> + mmap_unlock(); >>> + cpu_loop_exit(cpu); >> Given our other discussions about lock resetting I wonder if this is >> another case where mmap_reset() could be called on cpu_loop_exit? > > As I can see, this is the only place mmap_unlock() have to be called > right before cpu_loop_exit(). As I remember, all the other cased in > user-mode emulation were restructured by Peter M. in his syscall/signal > handling series. However, I like the idea to ensure that 'mmap_lock' is > released on any cpu_loop_exit(). What do maintainers think? > > Kind regards, > Sergey > >> >>> } >>> >>> gen_code_buf = tcg_ctx.code_gen_ptr; >> Otherwise so far the testing is looking pretty positive in linux-user: >> >> Tested-by: Alex Bennée <alex.ben...@linaro.org> >> Reviewed-by: Alex Bennée <alex.ben...@linaro.org>
I should add for the testing to fail without this series I had to apply the hot-path fixes otherwise lock contention has a serialising affect on the flushes anyway. >> >> >> -- >> Alex Bennée -- Alex Bennée