[PATCH 03/21] Remove use of signalfd in block-raw-posix.c

[Anthony Liguori <aliguori@xxxxxxxxxx>]

We don't use signalfd in upstream QEMU.  Instead, we always emulate it.

It's not necessarily a bad thing to use signalfd, but this is something that
should be done upstream.  It certainly does qemu-kvm no harm to use the upstream
code.

Signed-off-by: Anthony Liguori <aliguori@xxxxxxxxxx>
---
 block-raw-posix.c |   71 +++++++++++++++++++++++++++-------------------------
 1 files changed, 37 insertions(+), 34 deletions(-)

diff --git a/block-raw-posix.c b/block-raw-posix.c
index f033bae..822839f 100644
--- a/block-raw-posix.c
+++ b/block-raw-posix.c
@@ -25,7 +25,6 @@
 #include "qemu-timer.h"
 #include "qemu-char.h"
 #include "block_int.h"
-#include "compatfd.h"
 #include <assert.h>
 #ifdef CONFIG_AIO
 #include "posix-aio-compat.h"
@@ -481,7 +480,7 @@ typedef struct RawAIOCB {
 
 typedef struct PosixAioState
 {
-    int fd;
+    int rfd, wfd;
     RawAIOCB *first_aio;
 } PosixAioState;
 
@@ -490,29 +489,18 @@ static void posix_aio_read(void *opaque)
     PosixAioState *s = opaque;
     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(s->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;
-        }
+    ssize_t len;
+
+    /* read all bytes from signal pipe */
+    for (;;) {
+        char bytes[16];
 
-        offset += len;
+        len = read(s->rfd, bytes, sizeof(bytes));
+        if (len == -1 && errno == EINTR)
+            continue; /* try again */
+        if (len == sizeof(bytes))
+            continue; /* more to read */
+        break;
     }
 
     for(;;) {
@@ -559,10 +547,22 @@ static int posix_aio_flush(void *opaque)
 
 static PosixAioState *posix_aio_state;
 
+static void aio_signal_handler(int signum)
+{
+    if (posix_aio_state) {
+        char byte = 0;
+
+        write(posix_aio_state->wfd, &byte, sizeof(byte));
+    }
+
+    qemu_service_io();
+}
+
 static int posix_aio_init(void)
 {
-    sigset_t mask;
+    struct sigaction act;
     PosixAioState *s;
+    int fds[2];
     struct qemu_paioinit ai;
   
     if (posix_aio_state)
@@ -570,21 +570,24 @@ static int posix_aio_init(void)
 
     s = qemu_malloc(sizeof(PosixAioState));
 
-    /* Make sure to block AIO signal */
-    sigemptyset(&mask);
-    sigaddset(&mask, SIGUSR2);
-    sigprocmask(SIG_BLOCK, &mask, NULL);
+    sigfillset(&act.sa_mask);
+    act.sa_flags = 0; /* do not restart syscalls to interrupt select() */
+    act.sa_handler = aio_signal_handler;
+    sigaction(SIGUSR2, &act, NULL);
 
     s->first_aio = NULL;
-    s->fd = qemu_signalfd(&mask);
-    if (s->fd == -1) {
-        fprintf(stderr, "failed to create signalfd\n");
+    if (pipe(fds) == -1) {
+        fprintf(stderr, "failed to create pipe\n");
         return -errno;
     }
 
-    fcntl(s->fd, F_SETFL, O_NONBLOCK);
+    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->fd, posix_aio_read, NULL, posix_aio_flush, s);
+    qemu_aio_set_fd_handler(s->rfd, posix_aio_read, NULL, posix_aio_flush, s);
 
     memset(&ai, 0, sizeof(ai));
     ai.aio_threads = 64;
-- 
1.6.0.6

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