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block: make raw aio signaling non-blocking.

PATCH Applied Gerd Hoffmann 2 participants 2 messages Nov 13, 2008

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Gerd Hoffmann

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#0 lore raw

PATCH 1/1 block: make raw aio signaling non-blocking.

Hi,

This patch switches the read handle of the signaling pipe into non-blocking mode. This avoids unwanted blocking reads and also allows to read all bytes out of the signaling pipe in case we got signaled more that once before the handler ran.

cheers,
Gerd

Quoted 1 line

From 2b75aad0848fb231a0b942bd768f1e84462d1525 Mon Sep 17 00:00:00 2001

From: Gerd Hoffmann <[email protected]>
Date: Thu, 13 Nov 2008 14:21:19 +0100
Subject: [PATCH] block: make raw aio signaling non-blocking.

This patch switches the read handle of the signaling pipe into non-blocking mode. This avoids unwanted blocking reads and also allows to read all bytes out of the signaling pipe in case we got signaled more that once before the handler ran.

Signed-off-by Gerd Hoffmann <[email protected]>
---
 block-raw-posix.c |   17 ++++++++++-------
 1 files changed, 10 insertions(+), 7 deletions(-)
block-raw-posix.c +10 -7
index c06e38d..0a06a12 100644
@@ -497,15 +497,17 @@ static void posix_aio_read(void *opaque)
     int ret;
     ssize_t len;
 
-    do {
-        char byte;
+    /* read all bytes from signal pipe */
+    for (;;) {
+        char bytes[16];
 
-        len = read(s->rfd, &byte, 1);
+        len = read(s->rfd, bytes, sizeof(bytes));
         if (len == -1 && errno == EINTR)
-            continue;
-        if (len == -1 && errno == EAGAIN)
-            break;
-    } while (len == -1);
+            continue; /* try again */
+        if (len == sizeof(bytes))
+            continue; /* more to read */
+        break;
+    }
 
     for(;;) {
         pacb = &s->first_aio;

@@ -591,6 +593,7 @@ static int posix_aio_init(void)
     s->rfd = fds[0];
     s->wfd = fds[1];
 
+    fcntl(s->rfd, F_SETFL, O_NONBLOCK);
     fcntl(s->wfd, F_SETFL, O_NONBLOCK);
 
     qemu_aio_set_fd_handler(s->rfd, posix_aio_read, NULL, posix_aio_flush, s);
Signature · 1 line
1.5.6.5
Applied
#1 lore raw
Quoted 7 lines · Gerd Hoffmann

Hi,

This patch switches the read handle of the signaling pipe into non-blocking mode. This avoids unwanted blocking reads and also allows to read all bytes out of the signaling pipe in case we got signaled more that once before the handler ran.

Applied. Thanks.

Regards,

Anthony Liguori

Quoted 4 lines

cheers,
Gerd