Don't delete local watchpoints just because a different thread stopped.
Daniel Jacobowitz
drow@false.org
Thu Nov 19 17:46:00 GMT 2009
On Thu, Nov 19, 2009 at 02:07:01AM +0000, Pedro Alves wrote:
> One could even come up with a test case where the current
> frame id on this other thread does happen to be in the
> frame chain. Shouldn't be hard to trigger if the threads
> are running the same function --- GDB can then mistakenly
> try to extract a new current watchpoint value on the wrong
> thread context.
I hope your threads have different stacks :-) So I don't think this
case happens.
> Index: src/gdb/breakpoint.h
> ===================================================================
> --- src.orig/gdb/breakpoint.h 2009-11-19 01:10:05.000000000 +0000
> +++ src/gdb/breakpoint.h 2009-11-19 01:10:16.000000000 +0000
> @@ -457,6 +457,10 @@ struct breakpoint
> should be evaluated on the outermost frame. */
> struct frame_id watchpoint_frame;
>
> + /* Holds the thread which identifies the frame this watchpoint
> + should be considered in scope for, or -1 if don't care. */
> + int watchpoint_thread;
> +
> /* For hardware watchpoints, the triggered status according to the
> hardware. */
> enum watchpoint_triggered watchpoint_triggered;
Why not just use a ptid? If the answer has to do with ptid reuse,
then we ought to delete the watchpoint before that comes up - anyway,
at least deserves a comment of what units this is in.
> @@ -1004,6 +1028,12 @@ update_watchpoint (struct breakpoint *b,
> bpstat bs;
> struct program_space *frame_pspace;
>
> + /* If this is a local watchpoint, we only want to check if the
> + watchpoint frame is in scope if the current thread is the thread
> + that was used to create the watchpoint. */
> + if (!watchpoint_thread_match (b))
> + return;
> +
> /* We don't free locations. They are stored in bp_location array and
> update_global_locations will eventually delete them and remove
> breakpoints if needed. */
For all-stop, do we want to check whenever the watchpoint's thread is
stopped?
--
Daniel Jacobowitz
CodeSourcery
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