From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51007) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bNcPl-0005D4-R4 for qemu-devel@nongnu.org; Thu, 14 Jul 2016 04:54:39 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bNcPf-0002UI-T4 for qemu-devel@nongnu.org; Thu, 14 Jul 2016 04:54:36 -0400 Received: from mail-lf0-x241.google.com ([2a00:1450:4010:c07::241]:34553) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bNcPf-0002U7-KE for qemu-devel@nongnu.org; Thu, 14 Jul 2016 04:54:31 -0400 Received: by mail-lf0-x241.google.com with SMTP id l69so486410lfg.1 for ; Thu, 14 Jul 2016 01:54:31 -0700 (PDT) References: <1467839703-11733-1-git-send-email-sergey.fedorov@linaro.org> <1467839703-11733-12-git-send-email-sergey.fedorov@linaro.org> <8737nc627d.fsf@linaro.org> From: Sergey Fedorov Message-ID: <57875345.8020501@gmail.com> Date: Thu, 14 Jul 2016 11:54:29 +0300 MIME-Version: 1.0 In-Reply-To: <8737nc627d.fsf@linaro.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Subject: Re: [Qemu-devel] [RFC v2 11/11] tcg: Make tb_flush() thread safe List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: =?UTF-8?Q?Alex_Benn=c3=a9e?= , Sergey Fedorov Cc: qemu-devel@nongnu.org, MTTCG Devel , =?UTF-8?B?S09OUkFEIEZyw6lkw6lyaWM=?= , Alvise Rigo , "Emilio G. Cota" , Paolo Bonzini , Richard Henderson , Peter Maydell , Peter Crosthwaite On 14/07/16 11:41, Alex Bennée wrote: > Sergey Fedorov writes: > >> From: Sergey Fedorov >> >> Use async_safe_run_on_cpu() to make tb_flush() thread safe. >> >> Signed-off-by: Sergey Fedorov >> Signed-off-by: Sergey Fedorov >> --- >> >> 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 > Reviewed-by: Alex Bennée > > > -- > Alex Bennée