diff options
| author | cinap_lenrek <cinap_lenrek@felloff.net> | 2018-11-18 03:37:04 +0100 |
|---|---|---|
| committer | cinap_lenrek <cinap_lenrek@felloff.net> | 2018-11-18 03:37:04 +0100 |
| commit | 064ea89caa3d8b2183ad5827ee124c1213286e0c (patch) | |
| tree | 830276827da9ff784d8253d5679a9fc5e2b32e00 /sys/src/libdraw | |
| parent | a25418fddcf958c8a585779c7642bb88ceaf3f66 (diff) | |
libdraw: avoid deadlock for mouse ioproc sending on resizec
a deadlock has been observed with samterm (thanks burnzez),
that shows the mouse ioproc being stuck in sending on the
resize channel, while the mouse consumer is stuck in a
readmouse() loop wanting a rectangle to be drawn by the
user:
recv(v=0x42df50)+0x28 /sys/src/libthread/channel.c:321
readmouse(mc=0x42df50)+0x54 /sys/src/libdraw/mouse.c:34
getrect(.ret=0x41bce0,but=0x4,mc=0x42df50)+0x62 /sys/src/libdraw/getrect.c:49
r=0x41bc70
rc=0x41bc70
getr(rp=0x41bce0)+0x24 /sys/src/cmd/samterm/main.c:244
p=0x6b000004f6
r=0x2
sweeptext(new=0x0,tag=0x2d)+0x12 /sys/src/cmd/samterm/menu.c:208
r=0x2
t=0x42df50
inmesg(type=0x2,count=0x2)+0x1ab /sys/src/cmd/samterm/mesg.c:136
m=0x10000002d
l=0x2d00001b00
i=0x43829000000001
t=0x438290
lp=0x42e050
rcv()+0x7a /sys/src/cmd/samterm/mesg.c:77
threadmain(argv=0x7ffffeffef90)+0x173 /sys/src/cmd/samterm/main.c:63
so avoid blocking in the mouse ioproc by using nbsend()
instead of send() for writing to the resize channel.
Diffstat (limited to 'sys/src/libdraw')
| -rw-r--r-- | sys/src/libdraw/mouse.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/sys/src/libdraw/mouse.c b/sys/src/libdraw/mouse.c index 984ae3350..3ae6d5cc7 100644 --- a/sys/src/libdraw/mouse.c +++ b/sys/src/libdraw/mouse.c @@ -66,7 +66,7 @@ _ioproc(void *arg) switch(buf[0]){ case 'r': one = 1; - if(send(mc->resizec, &one) < 0) + if(nbsend(mc->resizec, &one) < 0) continue; /* fall through */ case 'm': @@ -122,7 +122,7 @@ initmouse(char *file, Image *i) free(t); mc->image = i; mc->c = chancreate(sizeof(Mouse), 0); - mc->resizec = chancreate(sizeof(int), 2); + mc->resizec = chancreate(sizeof(int), 1); mc->pid = proccreate(_ioproc, mc, 4096); return mc; } |