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

Anthony Liguori
2009-04-29T21:20:51Z

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@us.ibm.com>
---
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