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author | Vairavan Srinivasan <vairav@codeaurora.org> | 2011-02-14 20:45:59 -0800 |
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committer | Vairavan Srinivasan <vairav@codeaurora.org> | 2011-02-15 21:42:57 -0800 |
commit | 68a4e0a38fca00e9615a3c8ccb2d46edc88cf338 (patch) | |
tree | d5ea21e9142b957949f6ef1710572116fab7a002 | |
parent | 7d234fabe61cd5f034fe4ff4484209fbf5130c4d (diff) | |
download | frameworks_base-68a4e0a38fca00e9615a3c8ccb2d46edc88cf338.zip frameworks_base-68a4e0a38fca00e9615a3c8ccb2d46edc88cf338.tar.gz frameworks_base-68a4e0a38fca00e9615a3c8ccb2d46edc88cf338.tar.bz2 |
frameworks/base: acquire lock on am only when needed
appendDropBoxProcessHeaders acquires a lock on am while accessing
ProcessRecord (even if it is null). Watchdog thread ends up invoking
this function (with a null ProcessRecord) to add the stack file to
dropbox. This function would block if and when the watchdog thread is
invoked due to unavailability of lock on am resulting in a deadlock.
This would prevent watchdog from killing system_server.
Change-Id: Ieb34b767779cb587e0c5f536b9b7ba44fb9a28d9
-rw-r--r-- | services/java/com/android/server/am/ActivityManagerService.java | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/services/java/com/android/server/am/ActivityManagerService.java b/services/java/com/android/server/am/ActivityManagerService.java index 2322ee1..92721fe 100644 --- a/services/java/com/android/server/am/ActivityManagerService.java +++ b/services/java/com/android/server/am/ActivityManagerService.java @@ -6730,18 +6730,25 @@ public final class ActivityManagerService extends ActivityManagerNative * to append various headers to the dropbox log text. */ private void appendDropBoxProcessHeaders(ProcessRecord process, StringBuilder sb) { + // Watchdog thread ends up invoking this function (with + // a null ProcessRecord) to add the stack file to dropbox. + // Do not acquire a lock on this (am) in such cases, as it + // could cause a potential deadlock, if and when watchdog + // is invoked due to unavailability of lock on am and it + // would prevent watchdog from killing system_server. + if (process == null) { + sb.append("Process: system_server\n"); + return; + } // Note: ProcessRecord 'process' is guarded by the service // instance. (notably process.pkgList, which could otherwise change // concurrently during execution of this method) synchronized (this) { - if (process == null || process.pid == MY_PID) { + if (process.pid == MY_PID) { sb.append("Process: system_server\n"); } else { sb.append("Process: ").append(process.processName).append("\n"); } - if (process == null) { - return; - } int flags = process.info.flags; IPackageManager pm = AppGlobals.getPackageManager(); sb.append("Flags: 0x").append(Integer.toString(flags, 16)).append("\n"); |