| Message ID | 20180827222322.26009-7-marcandre.lureau@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | chardev: various cleanups and improvements | expand |
On Tue, Aug 28, 2018 at 12:23:19AM +0200, Marc-André Lureau wrote: > terminal3270 is uses the front-end side of the chardev. It shouldn't > create sources from backend side context. Fwiw, send_timing_mark_cb > calls qemu_chr_fe_write_all() which should be thread safe. > > This partially reverts changes from commit > 2c716ba1506769c9be2caa02f0f6d6e7c00f4304. I don't fully understand too on why "It shouldn't create sources from backend side context". Could you explain a bit? If you don't want the backend gcontext to be exposed to the frontend, IMHO the simplest thing is just to use the NULL gcontext in qemu_chr_timeout_add_ms() which is a one-liner change. I don't see much point on re-using the GSource tags since IMHO GSource pointer is always superior to the old tag system. > > CC: Peter Xu <peterx@redhat.com> > Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com> > --- > hw/char/terminal3270.c | 15 ++++++--------- > 1 file changed, 6 insertions(+), 9 deletions(-) > > diff --git a/hw/char/terminal3270.c b/hw/char/terminal3270.c > index e9c45e55b1..35b079d5c4 100644 > --- a/hw/char/terminal3270.c > +++ b/hw/char/terminal3270.c > @@ -31,7 +31,7 @@ typedef struct Terminal3270 { > uint8_t outv[OUTPUT_BUFFER_SIZE]; > int in_len; > bool handshake_done; > - GSource *timer_src; > + guint timer_tag; > } Terminal3270; > > #define TYPE_TERMINAL_3270 "x-terminal3270" > @@ -47,10 +47,9 @@ static int terminal_can_read(void *opaque) > > static void terminal_timer_cancel(Terminal3270 *t) > { > - if (t->timer_src) { > - g_source_destroy(t->timer_src); > - g_source_unref(t->timer_src); > - t->timer_src = NULL; > + if (t->timer_tag) { > + g_source_remove(t->timer_tag); > + t->timer_tag = 0; > } > } > > @@ -100,8 +99,7 @@ static void terminal_read(void *opaque, const uint8_t *buf, int size) > assert(size <= (INPUT_BUFFER_SIZE - t->in_len)); > > terminal_timer_cancel(t); > - t->timer_src = qemu_chr_timeout_add_ms(t->chr.chr, 600 * 1000, > - send_timing_mark_cb, t); > + t->timer_tag = g_timeout_add_seconds(600, send_timing_mark_cb, t); > memcpy(&t->inv[t->in_len], buf, size); > t->in_len += size; > if (t->in_len < 2) { > @@ -160,8 +158,7 @@ static void chr_event(void *opaque, int event) > * char-socket.c. Once qemu receives the terminal-type of the > * client, mark handshake done and trigger everything rolling again. > */ > - t->timer_src = qemu_chr_timeout_add_ms(t->chr.chr, 600 * 1000, > - send_timing_mark_cb, t); > + t->timer_tag = g_timeout_add_seconds(600, send_timing_mark_cb, t); > break; > case CHR_EVENT_CLOSED: > sch->curr_status.scsw.dstat = SCSW_DSTAT_DEVICE_END; > -- > 2.18.0.547.g1d89318c48 > Regards,
Hi On Tue, Aug 28, 2018 at 5:52 AM Peter Xu <peterx@redhat.com> wrote: > > On Tue, Aug 28, 2018 at 12:23:19AM +0200, Marc-André Lureau wrote: > > terminal3270 is uses the front-end side of the chardev. It shouldn't > > create sources from backend side context. Fwiw, send_timing_mark_cb > > calls qemu_chr_fe_write_all() which should be thread safe. > > > > This partially reverts changes from commit > > 2c716ba1506769c9be2caa02f0f6d6e7c00f4304. > > I don't fully understand too on why "It shouldn't create sources from > backend side context". Could you explain a bit? A frontend shouldn't use a backend function, and doesn't have to use the backend gmaincontext. > > If you don't want the backend gcontext to be exposed to the frontend, > IMHO the simplest thing is just to use the NULL gcontext in > qemu_chr_timeout_add_ms() which is a one-liner change. I don't see > much point on re-using the GSource tags since IMHO GSource pointer is > always superior to the old tag system. Using the tag or the GSource * doesn't change much afaik. Not only this is not a hot path, but glib gmain code does create the tag on attach anyway. You may be marginally faster on remove/detach by avoiding one lookup. (btw, I think both tag and GSource* are as old) > > > > > CC: Peter Xu <peterx@redhat.com> > > Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com> > > --- > > hw/char/terminal3270.c | 15 ++++++--------- > > 1 file changed, 6 insertions(+), 9 deletions(-) > > > > diff --git a/hw/char/terminal3270.c b/hw/char/terminal3270.c > > index e9c45e55b1..35b079d5c4 100644 > > --- a/hw/char/terminal3270.c > > +++ b/hw/char/terminal3270.c > > @@ -31,7 +31,7 @@ typedef struct Terminal3270 { > > uint8_t outv[OUTPUT_BUFFER_SIZE]; > > int in_len; > > bool handshake_done; > > - GSource *timer_src; > > + guint timer_tag; > > } Terminal3270; > > > > #define TYPE_TERMINAL_3270 "x-terminal3270" > > @@ -47,10 +47,9 @@ static int terminal_can_read(void *opaque) > > > > static void terminal_timer_cancel(Terminal3270 *t) > > { > > - if (t->timer_src) { > > - g_source_destroy(t->timer_src); > > - g_source_unref(t->timer_src); > > - t->timer_src = NULL; > > + if (t->timer_tag) { > > + g_source_remove(t->timer_tag); > > + t->timer_tag = 0; > > } > > } > > > > @@ -100,8 +99,7 @@ static void terminal_read(void *opaque, const uint8_t *buf, int size) > > assert(size <= (INPUT_BUFFER_SIZE - t->in_len)); > > > > terminal_timer_cancel(t); > > - t->timer_src = qemu_chr_timeout_add_ms(t->chr.chr, 600 * 1000, > > - send_timing_mark_cb, t); > > + t->timer_tag = g_timeout_add_seconds(600, send_timing_mark_cb, t); > > memcpy(&t->inv[t->in_len], buf, size); > > t->in_len += size; > > if (t->in_len < 2) { > > @@ -160,8 +158,7 @@ static void chr_event(void *opaque, int event) > > * char-socket.c. Once qemu receives the terminal-type of the > > * client, mark handshake done and trigger everything rolling again. > > */ > > - t->timer_src = qemu_chr_timeout_add_ms(t->chr.chr, 600 * 1000, > > - send_timing_mark_cb, t); > > + t->timer_tag = g_timeout_add_seconds(600, send_timing_mark_cb, t); > > break; > > case CHR_EVENT_CLOSED: > > sch->curr_status.scsw.dstat = SCSW_DSTAT_DEVICE_END; > > -- > > 2.18.0.547.g1d89318c48 > > > > Regards, > > -- > Peter Xu >
On Tue, Aug 28, 2018 at 11:09:28AM +0200, Marc-André Lureau wrote: > Hi > > On Tue, Aug 28, 2018 at 5:52 AM Peter Xu <peterx@redhat.com> wrote: > > > > On Tue, Aug 28, 2018 at 12:23:19AM +0200, Marc-André Lureau wrote: > > > terminal3270 is uses the front-end side of the chardev. It shouldn't > > > create sources from backend side context. Fwiw, send_timing_mark_cb > > > calls qemu_chr_fe_write_all() which should be thread safe. > > > > > > This partially reverts changes from commit > > > 2c716ba1506769c9be2caa02f0f6d6e7c00f4304. > > > > I don't fully understand too on why "It shouldn't create sources from > > backend side context". Could you explain a bit? > > A frontend shouldn't use a backend function, and doesn't have to use > the backend gmaincontext. > > > > > If you don't want the backend gcontext to be exposed to the frontend, > > IMHO the simplest thing is just to use the NULL gcontext in > > qemu_chr_timeout_add_ms() which is a one-liner change. I don't see > > much point on re-using the GSource tags since IMHO GSource pointer is > > always superior to the old tag system. > > Using the tag or the GSource * doesn't change much afaik. I did some convertions in the past year to convert tag -> GSource and that shows some differences when we want non-default gcontexts... Otherwise I won't bother. :) > Not only > this is not a hot path, but glib gmain code does create the tag on > attach anyway. You may be marginally faster on remove/detach by > avoiding one lookup. > > (btw, I think both tag and GSource* are as old) I am not strong on this, but my rule is that if I don't have explicit reason to change a code I keep it there. Here I don't see an obvious reason to switch back to the tag things (not to mention that I still think GSource is better, always). Thanks,
Hi On Tue, Aug 28, 2018 at 12:20 PM Peter Xu <peterx@redhat.com> wrote: > > On Tue, Aug 28, 2018 at 11:09:28AM +0200, Marc-André Lureau wrote: > > Hi > > > > On Tue, Aug 28, 2018 at 5:52 AM Peter Xu <peterx@redhat.com> wrote: > > > > > > On Tue, Aug 28, 2018 at 12:23:19AM +0200, Marc-André Lureau wrote: > > > > terminal3270 is uses the front-end side of the chardev. It shouldn't > > > > create sources from backend side context. Fwiw, send_timing_mark_cb > > > > calls qemu_chr_fe_write_all() which should be thread safe. > > > > > > > > This partially reverts changes from commit > > > > 2c716ba1506769c9be2caa02f0f6d6e7c00f4304. > > > > > > I don't fully understand too on why "It shouldn't create sources from > > > backend side context". Could you explain a bit? > > > > A frontend shouldn't use a backend function, and doesn't have to use > > the backend gmaincontext. > > > > > > > > If you don't want the backend gcontext to be exposed to the frontend, > > > IMHO the simplest thing is just to use the NULL gcontext in > > > qemu_chr_timeout_add_ms() which is a one-liner change. I don't see > > > much point on re-using the GSource tags since IMHO GSource pointer is > > > always superior to the old tag system. > > > > Using the tag or the GSource * doesn't change much afaik. > > I did some convertions in the past year to convert tag -> GSource and > that shows some differences when we want non-default gcontexts... > Otherwise I won't bother. :) It doesn't need a specific context here, does it? > > > Not only > > this is not a hot path, but glib gmain code does create the tag on > > attach anyway. You may be marginally faster on remove/detach by > > avoiding one lookup. > > > > (btw, I think both tag and GSource* are as old) > > I am not strong on this, but my rule is that if I don't have explicit > reason to change a code I keep it there. Here I don't see an obvious > reason to switch back to the tag things (not to mention that I still > think GSource is better, always). As I explained, you shouldn't use backend fonctions in the frontend, and there is no reason to use the backend context. I try to keep all the sources created around chardev under control, and this one is incorrect imho. Using g_timeout_add() is convenient, since it does all the work you do manually by creating a source, setting callback, attaching, unref etc. And it uses the default context, which is in general the right thing. I can do all the manual work and keep the GSource* around, but I don't think that helps in any way here. > > Thanks, > > -- > Peter Xu
diff --git a/hw/char/terminal3270.c b/hw/char/terminal3270.c index e9c45e55b1..35b079d5c4 100644 --- a/hw/char/terminal3270.c +++ b/hw/char/terminal3270.c @@ -31,7 +31,7 @@ typedef struct Terminal3270 { uint8_t outv[OUTPUT_BUFFER_SIZE]; int in_len; bool handshake_done; - GSource *timer_src; + guint timer_tag; } Terminal3270; #define TYPE_TERMINAL_3270 "x-terminal3270" @@ -47,10 +47,9 @@ static int terminal_can_read(void *opaque) static void terminal_timer_cancel(Terminal3270 *t) { - if (t->timer_src) { - g_source_destroy(t->timer_src); - g_source_unref(t->timer_src); - t->timer_src = NULL; + if (t->timer_tag) { + g_source_remove(t->timer_tag); + t->timer_tag = 0; } } @@ -100,8 +99,7 @@ static void terminal_read(void *opaque, const uint8_t *buf, int size) assert(size <= (INPUT_BUFFER_SIZE - t->in_len)); terminal_timer_cancel(t); - t->timer_src = qemu_chr_timeout_add_ms(t->chr.chr, 600 * 1000, - send_timing_mark_cb, t); + t->timer_tag = g_timeout_add_seconds(600, send_timing_mark_cb, t); memcpy(&t->inv[t->in_len], buf, size); t->in_len += size; if (t->in_len < 2) { @@ -160,8 +158,7 @@ static void chr_event(void *opaque, int event) * char-socket.c. Once qemu receives the terminal-type of the * client, mark handshake done and trigger everything rolling again. */ - t->timer_src = qemu_chr_timeout_add_ms(t->chr.chr, 600 * 1000, - send_timing_mark_cb, t); + t->timer_tag = g_timeout_add_seconds(600, send_timing_mark_cb, t); break; case CHR_EVENT_CLOSED: sch->curr_status.scsw.dstat = SCSW_DSTAT_DEVICE_END;
terminal3270 is uses the front-end side of the chardev. It shouldn't create sources from backend side context. Fwiw, send_timing_mark_cb calls qemu_chr_fe_write_all() which should be thread safe. This partially reverts changes from commit 2c716ba1506769c9be2caa02f0f6d6e7c00f4304. CC: Peter Xu <peterx@redhat.com> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com> --- hw/char/terminal3270.c | 15 ++++++--------- 1 file changed, 6 insertions(+), 9 deletions(-)