tree 817d634ba99dec2616cdefbe4bee442cedc55439
parent a684d9dad58eaac4d4833321ae92e7327057f18b
author Christopher Ferris <cferris@google.com> 1432854633 -0700
committer Christopher Ferris <cferris@google.com> 1433191911 -0700

Modify the code to avoid potential deadlocks.

If the signal to dump a thread is never delivered, then it's
possible for a deadlock. The signal handler is responsible for
unlocking and deleting the ThreadEntry created for the pid/tid
combination. This means if the signal is lost, the ThreadEntry
gets stuck locked and never deleted. If a second attempt to get
a backtrace of this thread occurs, there is a deadlock.

Also, decrease the timeout from 10 seconds to 5 seconds. The original
10 seconds was because the unwind was actually done in the signal
handler. Now the signal handler does nothing but copy the ucontext
structure and let the caller do the unwind.

Bug: 21086132
Change-Id: Idc735dbf6147ec879d35bd4f034c5d227e26a98d