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Revert "qemu-char: Keep pty slave file descriptor open until the master is closed"

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This reverts commit 34689e206abddac87a5217d458534e24f2a05562.

Marc-André Lureau provided the following commentary: "It looks like if
a the slave is opened, then Linux will buffer the master writes, up to
a few kb and then throttle, so it's not entirely blocked but eventually
the guest VM dies.  However, not having any slave open it will simply let
the write go and discard the data.  At least, virt-install configures
a pty for the serial but viewers like virt-manager do not necessarily
open it.  And, if there are no viewers, it will just hang.  If qemu
starts reading all the data from the slave, I don't think interactions
with other slaves will work. I don't see much options but to close the
slave, thus reverting this patch."

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2016-02-12 16:05:10 +01:00
parent 8800cf0a33
commit 837a183f00
1 changed files with 1 additions and 3 deletions
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4
qemu-char.c
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@ -1171,7 +1171,6 @@ typedef struct {
int connected; int connected;
guint timer_tag; guint timer_tag;
guint open_tag; guint open_tag;
int slave_fd;
} PtyCharDriver; } PtyCharDriver;
static void pty_chr_update_read_handler_locked(CharDriverState *chr); static void pty_chr_update_read_handler_locked(CharDriverState *chr);
@ -1348,7 +1347,6 @@ static void pty_chr_close(struct CharDriverState *chr)
qemu_mutex_lock(&chr->chr_write_lock); qemu_mutex_lock(&chr->chr_write_lock);
pty_chr_state(chr, 0); pty_chr_state(chr, 0);
close(s->slave_fd);
object_unref(OBJECT(s->ioc)); object_unref(OBJECT(s->ioc));
if (s->timer_tag) { if (s->timer_tag) {
g_source_remove(s->timer_tag); g_source_remove(s->timer_tag);
@ -1376,6 +1374,7 @@ static CharDriverState *qemu_chr_open_pty(const char *id,
return NULL; return NULL;
} }
close(slave_fd);
qemu_set_nonblock(master_fd); qemu_set_nonblock(master_fd);
chr = qemu_chr_alloc(common, errp); chr = qemu_chr_alloc(common, errp);
@ -1400,7 +1399,6 @@ static CharDriverState *qemu_chr_open_pty(const char *id,
chr->explicit_be_open = true; chr->explicit_be_open = true;
s->ioc = QIO_CHANNEL(qio_channel_file_new_fd(master_fd)); s->ioc = QIO_CHANNEL(qio_channel_file_new_fd(master_fd));
s->slave_fd = slave_fd;
s->timer_tag = 0; s->timer_tag = 0;
return chr; return chr;