88 lines
2.2 KiB
Diff
88 lines
2.2 KiB
Diff
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Improve suspend eventchn lock, use flock instead of exclusive lock
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file to avoid that sometimes the lock file is not removed cleanly
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and affacts later getting lock.
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http://lists.xensource.com/archives/html/xen-devel/2010-11/msg01559.html
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Signed-off-by cyliu@novell.com
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Index: xen-4.0.1-testing/tools/libxc/xc_suspend.c
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===================================================================
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--- xen-4.0.1-testing.orig/tools/libxc/xc_suspend.c
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+++ xen-4.0.1-testing/tools/libxc/xc_suspend.c
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@@ -6,25 +6,25 @@
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#include "xc_private.h"
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#include "xenguest.h"
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+#include <sys/file.h>
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+#include <sys/fcntl.h>
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#define SUSPEND_LOCK_FILE "/var/lib/xen/suspend_evtchn_lock.d"
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static int lock_suspend_event(void)
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{
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int fd, rc;
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mode_t mask;
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- char buf[128];
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mask = umask(022);
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- fd = open(SUSPEND_LOCK_FILE, O_CREAT | O_EXCL | O_RDWR, 0666);
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+ fd = open(SUSPEND_LOCK_FILE, O_CREAT | O_RDWR, 0666);
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if (fd < 0)
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{
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ERROR("Can't create lock file for suspend event channel\n");
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return -EINVAL;
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}
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umask(mask);
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- snprintf(buf, sizeof(buf), "%10ld", (long)getpid());
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+ rc = flock(fd, LOCK_EX | LOCK_NB);
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- rc = write_exact(fd, buf, strlen(buf));
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close(fd);
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return rc;
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@@ -32,30 +32,21 @@ static int lock_suspend_event(void)
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static int unlock_suspend_event(void)
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{
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- int fd, pid, n;
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- char buf[128];
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+ int fd, rc;
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fd = open(SUSPEND_LOCK_FILE, O_RDWR);
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if (fd < 0)
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return -EINVAL;
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- n = read(fd, buf, 127);
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+ rc = flock(fd, LOCK_UN | LOCK_NB);
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close(fd);
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- if (n > 0)
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- {
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- sscanf(buf, "%d", &pid);
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- /* We are the owner, so we can simply delete the file */
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- if (pid == getpid())
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- {
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- unlink(SUSPEND_LOCK_FILE);
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- return 0;
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- }
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- }
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+ if(!rc)
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+ unlink(SUSPEND_LOCK_FILE);
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- return -EPERM;
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+ return rc;
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}
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int xc_await_suspend(int xce, int suspend_evtchn)
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@@ -110,8 +101,7 @@ int xc_suspend_evtchn_init(int xc, int x
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return suspend_evtchn;
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cleanup:
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- if (suspend_evtchn != -1)
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- xc_suspend_evtchn_release(xce, suspend_evtchn);
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+ xc_suspend_evtchn_release(xce, suspend_evtchn);
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return -1;
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}
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