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[Qemu-devel] [PATCH 3/5] sclpconsole: remove bogus check for -EAGAIN
From: |
Daniel P. Berrange |
Subject: |
[Qemu-devel] [PATCH 3/5] sclpconsole: remove bogus check for -EAGAIN |
Date: |
Wed, 3 Aug 2016 17:22:38 +0100 |
The write_console_data() method in sclpconsole-lm.c checks
whether the return value of qemu_chr_fe_write() has the
value of -EAGAIN and if so then increments the buffer offset
by the value of EAGAIN. Fortunately qemu_chr_fe_write() will
never return EAGAIN directly, rather it returns -1 with
errno set to EAGAIN, so this broken code path was not
reachable. The behaviour on EAGAIN was stil bad though,
causing the write_console_data() to busy_wait repeatedly
calling qemu_chr_fe_write() with no sleep between iters.
Just remove all this loop logic and replace with a call
to qemu_chr_fe_write_all().
Signed-off-by: Daniel P. Berrange <address@hidden>
---
hw/char/sclpconsole-lm.c | 18 +++---------------
1 file changed, 3 insertions(+), 15 deletions(-)
diff --git a/hw/char/sclpconsole-lm.c b/hw/char/sclpconsole-lm.c
index a22ad8d..8cb0026 100644
--- a/hw/char/sclpconsole-lm.c
+++ b/hw/char/sclpconsole-lm.c
@@ -201,21 +201,9 @@ static int write_console_data(SCLPEvent *event, const
uint8_t *buf, int len)
return len;
}
- buf_offset = buf;
- while (len > 0) {
- ret = qemu_chr_fe_write(scon->chr, buf, len);
- if (ret == 0) {
- /* a pty doesn't seem to be connected - no error */
- len = 0;
- } else if (ret == -EAGAIN || (ret > 0 && ret < len)) {
- len -= ret;
- buf_offset += ret;
- } else {
- len = 0;
- }
- }
-
- return ret;
+ /* XXX this blocks entire thread. Rewrite to use
+ * qemu_chr_fe_write and background I/O callbacks */
+ return qemu_chr_fe_write_all(scon->chr, buf, len);
}
static int process_mdb(SCLPEvent *event, MDBO *mdbo)
--
2.7.4