| Message ID | 20230617053621.50359-6-bmeng@tinylab.org |
|---|---|
| State | New |
| Headers | show |
| Series | net/tap: Fix QEMU frozen issue when the maximum number of file descriptors is very large | expand |
On Sat, 17 Jun 2023 13:36:20 +0800 Bin Meng <bmeng@tinylab.org> wrote: > From: Zhangjin Wu <falcon@tinylab.org> > > Based on the old close_all_open_fd() of util/async-teardown.c, a new > generic qemu_close_range() has been added in osdep.c. > > Now, let's switch over to use the generic qemu_close_range(). > > Signed-off-by: Zhangjin Wu <falcon@tinylab.org> > Signed-off-by: Bin Meng <bmeng@tinylab.org> > > --- > > Changes in v3: > - limit the last_fd of qemu_close_range() to sysconf(_SC_OPEN_MAX) > > Changes in v2: > - new patch: "util/async-teardown: Use qemu_close_range() to close fds" > > util/async-teardown.c | 42 ++---------------------------------------- > 1 file changed, 2 insertions(+), 40 deletions(-) > > diff --git a/util/async-teardown.c b/util/async-teardown.c > index 7e0177a8da..e102912f3f 100644 > --- a/util/async-teardown.c > +++ b/util/async-teardown.c > @@ -29,44 +29,6 @@ > > static pid_t the_ppid; > > -/* > - * Close all open file descriptors. > - */ > -static void close_all_open_fd(void) > -{ > - struct dirent *de; > - int fd, dfd; > - DIR *dir; > - > -#ifdef CONFIG_CLOSE_RANGE > - int r = close_range(0, ~0U, 0); > - if (!r) { > - /* Success, no need to try other ways. */ > - return; > - } > -#endif > - > - dir = opendir("/proc/self/fd"); > - if (!dir) { > - /* If /proc is not mounted, close fds one by one. */ > - int open_max = sysconf(_SC_OPEN_MAX), i; > - for (i = 0; i < open_max; i++) { > - close(i); > - } > - return; > - } > - /* Avoid closing the directory. */ > - dfd = dirfd(dir); > - > - for (de = readdir(dir); de; de = readdir(dir)) { > - fd = atoi(de->d_name); > - if (fd != dfd) { > - close(fd); > - } > - } > - closedir(dir); > -} > - > static void hup_handler(int signal) > { > /* Check every second if this process has been reparented. */ > @@ -84,6 +46,7 @@ static int async_teardown_fn(void *arg) > struct sigaction sa = { .sa_handler = hup_handler }; > sigset_t hup_signal; > char name[16]; > + int open_max = sysconf(_SC_OPEN_MAX); > > /* Set a meaningful name for this process. */ > snprintf(name, 16, "cleanup/%d", the_ppid); > @@ -92,9 +55,8 @@ static int async_teardown_fn(void *arg) > /* > * Close all file descriptors that might have been inherited from the > * main qemu process when doing clone, needed to make libvirt happy. > - * Not using close_range for increased compatibility with older kernels. > */ > - close_all_open_fd(); > + qemu_close_range(0, open_max - 1); I think it would look easier to read if you just put the sysconf() call here and avoid an extra variable > > /* Set up a handler for SIGHUP and unblock SIGHUP. */ > sigaction(SIGHUP, &sa, NULL);
diff --git a/util/async-teardown.c b/util/async-teardown.c index 7e0177a8da..e102912f3f 100644 --- a/util/async-teardown.c +++ b/util/async-teardown.c @@ -29,44 +29,6 @@ static pid_t the_ppid; -/* - * Close all open file descriptors. - */ -static void close_all_open_fd(void) -{ - struct dirent *de; - int fd, dfd; - DIR *dir; - -#ifdef CONFIG_CLOSE_RANGE - int r = close_range(0, ~0U, 0); - if (!r) { - /* Success, no need to try other ways. */ - return; - } -#endif - - dir = opendir("/proc/self/fd"); - if (!dir) { - /* If /proc is not mounted, close fds one by one. */ - int open_max = sysconf(_SC_OPEN_MAX), i; - for (i = 0; i < open_max; i++) { - close(i); - } - return; - } - /* Avoid closing the directory. */ - dfd = dirfd(dir); - - for (de = readdir(dir); de; de = readdir(dir)) { - fd = atoi(de->d_name); - if (fd != dfd) { - close(fd); - } - } - closedir(dir); -} - static void hup_handler(int signal) { /* Check every second if this process has been reparented. */ @@ -84,6 +46,7 @@ static int async_teardown_fn(void *arg) struct sigaction sa = { .sa_handler = hup_handler }; sigset_t hup_signal; char name[16]; + int open_max = sysconf(_SC_OPEN_MAX); /* Set a meaningful name for this process. */ snprintf(name, 16, "cleanup/%d", the_ppid); @@ -92,9 +55,8 @@ static int async_teardown_fn(void *arg) /* * Close all file descriptors that might have been inherited from the * main qemu process when doing clone, needed to make libvirt happy. - * Not using close_range for increased compatibility with older kernels. */ - close_all_open_fd(); + qemu_close_range(0, open_max - 1); /* Set up a handler for SIGHUP and unblock SIGHUP. */ sigaction(SIGHUP, &sa, NULL);