On Mon, Oct 14, 2024 at 3:20 PM Marc-André Lureau
<marcandre.lur...@gmail.com> wrote:
>
>
>
> On Mon, Oct 14, 2024 at 3:45 PM Roman Penyaev <r.peni...@gmail.com> wrote:
>>
>> Frontends can be attached and detached during run-time (although detach
>> is not implemented, but will follow). Counter variable of muxes is not
>> enough for proper attach/detach management, so this patch implements
>> bitset: if bit is set for the `mux_bitset` variable, then frontend
>> device can be found in the `backend` array (yes, huge confusion with
>> backend and frontends names).
>>
>> Signed-off-by: Roman Penyaev <r.peni...@gmail.com>
>> Cc: "Marc-André Lureau" <marcandre.lur...@redhat.com>
>> Cc: qemu-devel@nongnu.org
>> ---
>> chardev/char-mux.c | 41 +++++++++++++++++++++++++-------------
>> chardev/char.c | 2 +-
>> chardev/chardev-internal.h | 2 +-
>> 3 files changed, 29 insertions(+), 16 deletions(-)
>>
>> diff --git a/chardev/char-mux.c b/chardev/char-mux.c
>> index 9294f955462e..9c3cacb2fecd 100644
>> --- a/chardev/char-mux.c
>> +++ b/chardev/char-mux.c
>> @@ -26,6 +26,7 @@
>> #include "qapi/error.h"
>> #include "qemu/module.h"
>> #include "qemu/option.h"
>> +#include "qemu/bitops.h"
>> #include "chardev/char.h"
>> #include "sysemu/block-backend.h"
>> #include "qapi/qapi-commands-control.h"
>> @@ -168,12 +169,19 @@ static int mux_proc_byte(Chardev *chr, MuxChardev *d,
>> int ch)
>> case 'b':
>> qemu_chr_be_event(chr, CHR_EVENT_BREAK);
>> break;
>> - case 'c':
>> - assert(d->mux_cnt > 0); /* handler registered with first fe */
>> + case 'c': {
>> + unsigned int bit;
>> +
>> + /* Handler registered with first fe */
>> + assert(d->mux_bitset != 0);
>> /* Switch to the next registered device */
>> - mux_set_focus(chr, (d->focus + 1) % d->mux_cnt);
>> + bit = find_next_bit(&d->mux_bitset, MAX_MUX, d->focus + 1);
>> + if (bit >= MAX_MUX) {
>> + bit = find_next_bit(&d->mux_bitset, MAX_MUX, 0);
>> + }
>> + mux_set_focus(chr, bit);
>> break;
>> - case 't':
>> + } case 't':
>> d->timestamps = !d->timestamps;
>> d->timestamps_start = -1;
>> d->linestart = false;
>> @@ -243,15 +250,16 @@ static void mux_chr_read(void *opaque, const uint8_t
>> *buf, int size)
>> void mux_chr_send_all_event(Chardev *chr, QEMUChrEvent event)
>> {
>> MuxChardev *d = MUX_CHARDEV(chr);
>> - unsigned int i;
>> + int bit;
>>
>> if (!muxes_opened) {
>> return;
>> }
>>
>> /* Send the event to all registered listeners */
>> - for (i = 0; i < d->mux_cnt; i++) {
>> - mux_chr_send_event(d, i, event);
>> + bit = -1;
>> + while ((bit = find_next_bit(&d->mux_bitset, MAX_MUX, bit + 1)) <
>> MAX_MUX) {
>> + mux_chr_send_event(d, bit, event);
>> }
>> }
>>
>> @@ -276,10 +284,11 @@ static GSource *mux_chr_add_watch(Chardev *s,
>> GIOCondition cond)
>> static void char_mux_finalize(Object *obj)
>> {
>> MuxChardev *d = MUX_CHARDEV(obj);
>> - unsigned int i;
>> + int bit;
>>
>> - for (i = 0; i < d->mux_cnt; i++) {
>> - CharBackend *be = d->backends[i];
>> + bit = -1;
>> + while ((bit = find_next_bit(&d->mux_bitset, MAX_MUX, bit + 1)) <
>> MAX_MUX) {
>> + CharBackend *be = d->backends[bit];
>> if (be) {
>> be->chr = NULL;
>> }
>> @@ -304,7 +313,10 @@ static void mux_chr_update_read_handlers(Chardev *chr)
>> bool mux_chr_attach_frontend(MuxChardev *d, CharBackend *b,
>> unsigned int *tag, Error **errp)
>> {
>> - if (d->mux_cnt >= MAX_MUX) {
>> + unsigned int bit;
>> +
>> + bit = find_next_zero_bit(&d->mux_bitset, MAX_MUX, 0);
>> + if (bit >= MAX_MUX) {
>> error_setg(errp,
>> "too many uses of multiplexed chardev '%s'"
>> " (maximum is " stringify(MAX_MUX) ")",
>> @@ -312,8 +324,9 @@ bool mux_chr_attach_frontend(MuxChardev *d, CharBackend
>> *b,
>> return false;
>> }
>>
>> - d->backends[d->mux_cnt] = b;
>> - *tag = d->mux_cnt++;
>> + d->mux_bitset |= (1 << bit);
>> + d->backends[bit] = b;
>> + *tag = bit;
>>
>> return true;
>> }
>> @@ -322,7 +335,7 @@ void mux_set_focus(Chardev *chr, unsigned int focus)
>> {
>> MuxChardev *d = MUX_CHARDEV(chr);
>>
>> - assert(focus < d->mux_cnt);
>> + assert(find_next_bit(&d->mux_bitset, MAX_MUX, focus) < MAX_MUX);
>
>
> Wouldn't this be more correct?
>
> + assert(find_next_bit(&d->mux_bitset, MAX_MUX, focus) == focus);
>
Yes, makes sense. Thanks.
Do you want the whole patchset to be resend,
or only changed patches with "v2" prefix in subject?
--
Roman
