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From: Anthony Liguori <anthony@codemonkey.ws>
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Date: Thu, 11 Sep 2008 14:32:27 +0000
Subject: [Qemu-devel] [5195] Make sure to read siginfo from signalfd
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Revision: 5195
          http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=5195
Author:   aliguori
Date:     2008-09-11 14:32:27 +0000 (Thu, 11 Sep 2008)

Log Message:
-----------
Make sure to read siginfo from signalfd

Otherwise, we'll idle at 100% cpu.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

Modified Paths:
--------------
    trunk/block-raw-posix.c

Modified: trunk/block-raw-posix.c
===================================================================
--- trunk/block-raw-posix.c	2008-09-11 14:18:56 UTC (rev 5194)
+++ trunk/block-raw-posix.c	2008-09-11 14:32:27 UTC (rev 5195)
@@ -449,7 +449,31 @@
 {
     RawAIOCB *acb, **pacb;
     int ret;
+    size_t offset;
+    union {
+        struct qemu_signalfd_siginfo siginfo;
+        char buf[128];
+    } sig;
 
+    /* try to read from signalfd, don't freak out if we can't read anything */
+    offset = 0;
+    while (offset < 128) {
+        ssize_t len;
+
+        len = read(aio_sig_fd, sig.buf + offset, 128 - offset);
+        if (len == -1 && errno == EINTR)
+            continue;
+        if (len == -1 && errno == EAGAIN) {
+            /* there is no natural reason for this to happen,
+             * so we'll spin hard until we get everything just
+             * to be on the safe side. */
+            if (offset > 0)
+                continue;
+        }
+
+        offset += len;
+    }
+
     for(;;) {
         pacb = &first_aio;
         for(;;) {
@@ -498,6 +522,9 @@
     sigprocmask(SIG_BLOCK, &mask, NULL);
     
     aio_sig_fd = qemu_signalfd(&mask);
+
+    fcntl(aio_sig_fd, F_SETFL, O_NONBLOCK);
+
 #if !defined(QEMU_IMG) && !defined(QEMU_NBD)
     qemu_set_fd_handler2(aio_sig_fd, NULL, qemu_aio_poll, NULL, NULL);
 #endif