[ovs-dev] [PATCH 1/2] lockfile: Improve log message when a process tries to relock a file.

[Ben Pfaff]

"Resource deadlock avoided" is a pretty obscure message.

Signed-off-by: Ben Pfaff <blp at nicira.com>
---
 lib/lockfile.c    |    6 +++++-
 tests/lockfile.at |   20 ++++++++++----------
 2 files changed, 15 insertions(+), 11 deletions(-)

diff --git a/lib/lockfile.c b/lib/lockfile.c
index c83f469..d157bc6 100644
--- a/lib/lockfile.c
+++ b/lib/lockfile.c
@@ -122,7 +122,10 @@ lockfile_lock(const char *file, struct lockfile **lockfilep)
         if (error == EACCES) {
             error = EAGAIN;
         }
-        if (pid) {
+        if (pid == getpid()) {
+            VLOG_WARN("%s: cannot lock file because this process has already "
+                      "locked it", lock_name);
+        } else if (pid) {
             VLOG_WARN("%s: cannot lock file because it is already locked by "
                       "pid %ld", lock_name, (long int) pid);
         } else {
@@ -307,6 +310,7 @@ lockfile_try_lock(const char *name, pid_t *pidp, struct lockfile **lockfilep)
     /* Check whether we've already got a lock on that file. */
     if (!stat(name, &s)) {
         if (lockfile_find(s.st_dev, s.st_ino)) {
+            *pidp = getpid();
             return EDEADLK;
         }
     } else if (errno != ENOENT) {
diff --git a/tests/lockfile.at b/tests/lockfile.at
index 2644d3f..d5f2eac 100644
--- a/tests/lockfile.at
+++ b/tests/lockfile.at
@@ -14,12 +14,12 @@ CHECK_LOCKFILE([lock_and_unlock], [0])
 CHECK_LOCKFILE([lock_and_unlock_twice], [0])
 
 CHECK_LOCKFILE([lock_blocks_same_process], [0],
-  [lockfile|WARN|.file.~lock~: failed to lock file: Resource deadlock avoided
+  [lockfile|WARN|.file.~lock~: cannot lock file because this process has already locked it
 ])
 
 CHECK_LOCKFILE([lock_blocks_same_process_twice], [0],
-  [lockfile|WARN|.file.~lock~: failed to lock file: Resource deadlock avoided
-lockfile|WARN|.file.~lock~: failed to lock file: Resource deadlock avoided
+  [lockfile|WARN|.file.~lock~: cannot lock file because this process has already locked it
+lockfile|WARN|.file.~lock~: cannot lock file because this process has already locked it
 ])
 
 CHECK_LOCKFILE([lock_blocks_other_process], [1],
@@ -28,7 +28,7 @@ lockfile|WARN|.file.~lock~: cannot lock file because it is already locked by pid
 ])
 
 CHECK_LOCKFILE([lock_twice_blocks_other_process], [1],
-  [lockfile|WARN|.file.~lock~: failed to lock file: Resource deadlock avoided
+  [lockfile|WARN|.file.~lock~: cannot lock file because this process has already locked it
 lockfile|WARN|.file.~lock~: child does not inherit lock
 lockfile|WARN|.file.~lock~: cannot lock file because it is already locked by pid <pid>
 ])
@@ -36,16 +36,16 @@ lockfile|WARN|.file.~lock~: cannot lock file because it is already locked by pid
 CHECK_LOCKFILE([lock_and_unlock_allows_other_process], [1])
 
 CHECK_LOCKFILE([lock_multiple], [0],
-  [lockfile|WARN|.a.~lock~: failed to lock file: Resource deadlock avoided
+  [lockfile|WARN|.a.~lock~: cannot lock file because this process has already locked it
 ])
 
 CHECK_LOCKFILE([lock_symlink], [0],
-  [lockfile|WARN|.a.~lock~: failed to lock file: Resource deadlock avoided
-lockfile|WARN|.b.~lock~: failed to lock file: Resource deadlock avoided
-lockfile|WARN|.b.~lock~: failed to lock file: Resource deadlock avoided
-lockfile|WARN|.a.~lock~: failed to lock file: Resource deadlock avoided
+  [lockfile|WARN|.a.~lock~: cannot lock file because this process has already locked it
+lockfile|WARN|.b.~lock~: cannot lock file because this process has already locked it
+lockfile|WARN|.b.~lock~: cannot lock file because this process has already locked it
+lockfile|WARN|.a.~lock~: cannot lock file because this process has already locked it
 ])
 
 CHECK_LOCKFILE([lock_symlink_to_dir], [0],
-  [lockfile|WARN|dir/.b.~lock~: failed to lock file: Resource deadlock avoided
+  [lockfile|WARN|dir/.b.~lock~: cannot lock file because this process has already locked it
 ])
-- 
1.7.10.4