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[Qemu-devel] [PATCH v2] gdbstub: avoid busy loop while waiting for gdb
From: |
Peter Wu |
Subject: |
[Qemu-devel] [PATCH v2] gdbstub: avoid busy loop while waiting for gdb |
Date: |
Sun, 5 Jun 2016 16:35:48 +0200 |
While waiting for a gdb response, or while sending an acknowledgement
there is not much to do, so do not mark the socket as non-blocking to
avoid a busy loop while paused at gdb. This only affects the user-mode
emulation (qemu-arm -g 1234 ./a.out).
Note that this issue was reported before at
https://lists.nongnu.org/archive/html/qemu-devel/2013-02/msg02277.html.
While at it, close the gdb client fd on EOF or error while reading.
Signed-off-by: Peter Wu <address@hidden>
Reviewed-by: Peter Maydell <address@hidden>
---
v2: resent with fixed commit message + R-b from
https://patchwork.kernel.org/patch/9008751/
---
gdbstub.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/gdbstub.c b/gdbstub.c
index 0e431fd..b126bf5 100644
--- a/gdbstub.c
+++ b/gdbstub.c
@@ -332,7 +332,7 @@ static int get_char(GDBState *s)
if (ret < 0) {
if (errno == ECONNRESET)
s->fd = -1;
- if (errno != EINTR && errno != EAGAIN)
+ if (errno != EINTR)
return -1;
} else if (ret == 0) {
close(s->fd);
@@ -393,7 +393,7 @@ static void put_buffer(GDBState *s, const uint8_t *buf, int
len)
while (len > 0) {
ret = send(s->fd, buf, len, 0);
if (ret < 0) {
- if (errno != EINTR && errno != EAGAIN)
+ if (errno != EINTR)
return;
} else {
buf += ret;
@@ -1542,9 +1542,13 @@ gdb_handlesig(CPUState *cpu, int sig)
for (i = 0; i < n; i++) {
gdb_read_byte(s, buf[i]);
}
- } else if (n == 0 || errno != EAGAIN) {
+ } else {
/* XXX: Connection closed. Should probably wait for another
connection before continuing. */
+ if (n == 0) {
+ close(s->fd);
+ }
+ s->fd = -1;
return sig;
}
}
@@ -1599,8 +1603,6 @@ static void gdb_accept(void)
gdb_has_xml = false;
gdbserver_state = s;
-
- fcntl(fd, F_SETFL, O_NONBLOCK);
}
static int gdbserver_open(int port)
--
2.8.3
- [Qemu-devel] [PATCH v2] gdbstub: avoid busy loop while waiting for gdb,
Peter Wu <=