| Message ID | 1467839703-11733-12-git-send-email-sergey.fedorov@linaro.org |
|---|---|
| State | New |
| Headers | show |
On 07/07/16 00:15, Sergey Fedorov wrote: > From: Sergey Fedorov <serge.fdrv@gmail.com> > > Use async_safe_run_on_cpu() to make tb_flush() thread safe. I've just realized that this allows to remove CPUState::tb_flushed as well. Regards, Sergey
Sergey Fedorov <sergey.fedorov@linaro.org> writes: > From: Sergey Fedorov <serge.fdrv@gmail.com> > > Use async_safe_run_on_cpu() to make tb_flush() thread safe. > > Signed-off-by: Sergey Fedorov <serge.fdrv@gmail.com> > Signed-off-by: Sergey Fedorov <sergey.fedorov@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? > } > > 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.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> -- Alex Bennée
On 14/07/16 11:41, Alex Bennée wrote: > Sergey Fedorov <sergey.fedorov@linaro.org> writes: > >> From: Sergey Fedorov <serge.fdrv@gmail.com> >> >> Use async_safe_run_on_cpu() to make tb_flush() thread safe. >> >> Signed-off-by: Sergey Fedorov <serge.fdrv@gmail.com> >> Signed-off-by: Sergey Fedorov <sergey.fedorov@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.bennee@linaro.org> > Reviewed-by: Alex Bennée <alex.bennee@linaro.org> > > > -- > Alex Bennée
Sergey Fedorov <serge.fdrv@gmail.com> writes: > On 14/07/16 11:41, Alex Bennée wrote: >> Sergey Fedorov <sergey.fedorov@linaro.org> writes: >> >>> From: Sergey Fedorov <serge.fdrv@gmail.com> >>> >>> Use async_safe_run_on_cpu() to make tb_flush() thread safe. >>> >>> Signed-off-by: Sergey Fedorov <serge.fdrv@gmail.com> >>> Signed-off-by: Sergey Fedorov <sergey.fedorov@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.bennee@linaro.org> >> Reviewed-by: Alex Bennée <alex.bennee@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
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); } gen_code_buf = tcg_ctx.code_gen_ptr;