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Linux gdbserver confused when event randomization picks process exit event

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The tail end of linux_wait_1 isn't expecting that the select_event_lwp
machinery can pick a whole-process exit event to report to GDB.  When
that happens, both gdb and gdbserver end up quite confused:

 ...
 (gdb)
 [Thread 24971.24971] #1 stopped.
 0x0000003615a011f0 in ?? ()
 c&
 Continuing.
 (gdb) [New Thread 24971.24981]
 [New Thread 24983.24983]
 [New Thread 24971.24982]

 [Thread 24983.24983] #3 stopped.
 0x0000003615ebc7cc in __libc_fork () at ../nptl/sysdeps/unix/sysv/linux/fork.c:130
 130       pid = ARCH_FORK ();
 [New Thread 24984.24984]
 Error in re-setting breakpoint -16: PC register is not available
 Error in re-setting breakpoint -17: PC register is not available
 Error in re-setting breakpoint -18: PC register is not available
 Error in re-setting breakpoint -19: PC register is not available
 Error in re-setting breakpoint -24: PC register is not available
 Error in re-setting breakpoint -25: PC register is not available
 Error in re-setting breakpoint -26: PC register is not available
 Error in re-setting breakpoint -27: PC register is not available
 Error in re-setting breakpoint -28: PC register is not available
 Error in re-setting breakpoint -29: PC register is not available
 Error in re-setting breakpoint -30: PC register is not available
 PC register is not available
 (gdb)

gdb/gdbserver/ChangeLog:
2015-08-06  Pedro Alves  <palves@redhat.com>

	* linux-low.c (add_lwp): Set waitstatus to TARGET_WAITKIND_IGNORE.
	(linux_thread_alive): Use lwp_is_marked_dead.
	(extended_event_reported): Delete.
	(linux_wait_1): Check if waitstatus is TARGET_WAITKIND_IGNORE
	instead of extended_event_reported.
	(mark_lwp_dead): Don't set the 'dead' flag.  Store the waitstatus
	as well.
	(lwp_is_marked_dead): New function.
	(lwp_running): Use lwp_is_marked_dead.
	* linux-low.h: Delete 'dead' field, and update 'waitstatus's
	comment.
This commit is contained in:
Pedro Alves 2015-08-06 10:30:17 +01:00
parent ad071a3055
commit 00db26facc
3 changed files with 54 additions and 35 deletions
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11
gdb/gdbserver/linux-low.h
View file

@ -261,16 +261,13 @@ struct lwp_info
event already received in a wait()). */
int stopped;
/* If this flag is set, the lwp is known to be dead already (exit
event already received in a wait(), and is cached in
status_pending). */
int dead;
/* When stopped is set, the last wait status recorded for this lwp. */
int last_status;
/* This is used to store extended ptrace event information until
it is reported to GDB. */
/* If WAITSTATUS->KIND != TARGET_WAITKIND_IGNORE, the waitstatus for
this LWP's last event, to pass to GDB without any further
processing. This is used to store extended ptrace event
information or exit status until it can be reported to GDB. */
struct target_waitstatus waitstatus;
/* When stopped is set, this is where the lwp last stopped, with