Re: [PATCH] [gdb/testsuite] Fix another timeout in gdb.base/bg-execution-repeat.exp

[Tom de Vries <tdevries@suse.de>]

On 4/16/25 17:26, Alexandra Petlanova Hajkova wrote:
> 
> 
> On Mon, Apr 14, 2025 at 1:51 PM Tom de Vries <tdevries@suse.de 
> <mailto:tdevries@suse.de>> wrote:
> 
>     With test-case gdb.base/bg-execution-repeat.exp, occasionally I run
>     into a
>     timeout:
>     ...
>     (gdb) c 1&
>     Will stop next time breakpoint 1 is reached.  Continuing.
>     (gdb) PASS: $exp: c 1&: c 1&
> 
>     Breakpoint 2, foo () at bg-execution-repeat.c:23
>     23        return 0; /* set break here */
>     PASS: $exp: c 1&: breakpoint hit 1
> 
>     Will stop next time breakpoint 2 is reached.  Continuing.
>     (gdb) PASS: $exp: c 1&: repeat bg command
>     print 1
>     $1 = 1
>     (gdb) PASS: $exp: c 1&: input still accepted
>     interrupt
>     (gdb) PASS: $exp: c 1&: interrupt
> 
>     Program received signal SIGINT, Interrupt.
>     foo () at bg-execution-repeat.c:24
>     24      }
>     PASS: $exp: c 1&: interrupt received
>     set var do_wait=0
>     (gdb) PASS: $exp: c 1&: set var do_wait=0
>     continue&
>     Continuing.
>     (gdb) PASS: $exp: c 1&: continue&
>     FAIL: $exp: c 1&: breakpoint hit 2 (timeout)
>     ...
> 
>     I can reproduce it reliably by adding a "sleep (1)" before the
>     "do_wait = 1"
>     in the .c file.
> 
>     The timeout happens as follows:
>     - with the inferior stopped at main, gdb continues (command c 1&)
>     - the inferior hits the breakpoint at foo
>     - gdb continues (using the repeat command functionality)
>     - the inferior is interrupted
>     - inferior variable do_wait gets set to 0.  The assumption here is
>     that the
>        inferior has progressed enough that do_wait is set to 1 at that
>     point, but
>        that happens not to be the case.  Consequently, this has no effect.
>     - gdb continues
>     - the inferior sets do_wait to 1
>     - the inferior enters the wait function, and wait for do_wait to
>     become 0,
>        which never happens.
> 
>     Fix this by moving the "do_wait = 1" to before the first call to foo.
> 
>     Tested on x86_64-linux.
>     ---
> 
> Hi Tom,
> 
> I also tested this on aarch64 and it works as expected, I think it's a 
> reasonable change.
> 

Hi Alexandra,

thanks for the review, pushed.

- Tom

> Reviewed-By: Alexandra Petlanova Hajkova <ahajkova@redhat.com 
> <mailto:ahajkova@redhat.com>>