Re: [patch] Fix linux-ia64 on SIGILL for deleted breakpoint [cleanup]

[Jan Kratochvil <jan dot kratochvil at redhat dot com>]

On Tue, 27 Jul 2010 13:59:18 +0200, Pedro Alves wrote:
> > +static int
> > +linux_nat_lp_status_is_event (struct lwp_info *lp)
> 
> Static helper functions that aren't a part of the target_ops
> interface (as opposed to linux_nat_resume, say), or external,
> don't usually take the "linux_nat_" prefix, so you could shorten
> the function name.

There is a problem that linux_nat_set_status_is_event is not static and
therefore it is correctly ^linux_nat_ prefixed.  I thought all the other
related functions should have matching name, which assigns them the incorrect
^linux_nat_ prefix.


> I'm not particularly fond of the function names.  The reason is
> that:
> 
> - linux_nat_status_is_event
> 
>     Returns true for breakpoint events, and other SIGTRAP events.
>     Returns false for other kinds of events (random signals), though
>     we could call these events too.
> 
> - linux_nat_lp_status_is_event
> 
>     Returns true for breakpoint events, and other SIGTRAP events
>     Returns false for other kinds of events (random signals), and
>     fork/exec/clone/exit events, though we could call these events too.
> 
> Note the subtle differences.

Yes... the problem is the variables already are not systematic.  There should
be that lp->status_p flag discussed in the comments, TARGET_SIGNAL_TRAP is
incorrectly used as an abstraction of inferior event (even for
SIGILL/SIGSEGV/etc.), lp->signalled should be called lp->sigstop_sent,
lp->resumed should be called lp->want_to_resume, target_signal should be
called gdb_signal, host signal should be called target signal,
lp->waitstatus.kind TARGET_WAITKIND_* I cannot describe right offhand now.

I have to admit I mostly gave up on building systematic functions and naming
on top of it.


> This appears to be changing behaviour (the new waitstatus check within
> the new function), but I doubt it makes a difference.  I'm pointing
> it out, because you're presenting the patch as cleanup.

Sorry for the naming, I did not indend to consider this patch as a no
functionality change patch.  (Although it should not be a user visible
change.)


Checked-in.


Thanks,
Jan


http://sourceware.org/ml/gdb-cvs/2010-07/msg00171.html

--- src/gdb/ChangeLog	2010/07/27 20:51:37	1.12026
+++ src/gdb/ChangeLog	2010/07/27 21:22:07	1.12027
@@ -1,5 +1,11 @@
 2010-07-27  Jan Kratochvil  <jan.kratochvil@redhat.com>
 
+	* linux-nat.c (linux_nat_lp_status_is_event): New function.
+	(count_events_callback, select_event_lwp_callback)
+	(cancel_breakpoints_callback, linux_nat_wait_1): Use it.
+
+2010-07-27  Jan Kratochvil  <jan.kratochvil@redhat.com>
+
 	* ia64-linux-nat.c (ia64_linux_status_is_event): New function.
 	(_initialize_ia64_linux_nat): Install it.
 	* linux-nat.c (sigtrap_is_event, linux_nat_status_is_event)
--- src/gdb/linux-nat.c	2010/07/27 20:51:37	1.179
+++ src/gdb/linux-nat.c	2010/07/27 21:22:09	1.180
@@ -2617,6 +2617,20 @@
 
 static int (*linux_nat_status_is_event) (int status) = sigtrap_is_event;
 
+/* Check for SIGTRAP-like events in LP.  */
+
+static int
+linux_nat_lp_status_is_event (struct lwp_info *lp)
+{
+  /* We check for lp->waitstatus in addition to lp->status, because we can
+     have pending process exits recorded in lp->status
+     and W_EXITCODE(0,0) == 0.  We should probably have an additional
+     lp->status_p flag.  */
+
+  return (lp->waitstatus.kind == TARGET_WAITKIND_IGNORE
+	  && linux_nat_status_is_event (lp->status));
+}
+
 /* Set alternative SIGTRAP-like events recognizer.  If
    breakpoint_inserted_here_p there then gdbarch_decr_pc_after_break will be
    applied.  */
@@ -2823,8 +2837,7 @@
   gdb_assert (count != NULL);
 
   /* Count only resumed LWPs that have a SIGTRAP event pending.  */
-  if (lp->status != 0 && lp->resumed
-      && linux_nat_status_is_event (lp->status))
+  if (lp->resumed && linux_nat_lp_status_is_event (lp))
     (*count)++;
 
   return 0;
@@ -2851,8 +2864,7 @@
   gdb_assert (selector != NULL);
 
   /* Select only resumed LWPs that have a SIGTRAP event pending. */
-  if (lp->status != 0 && lp->resumed
-      && linux_nat_status_is_event (lp->status))
+  if (lp->resumed && linux_nat_lp_status_is_event (lp))
     if ((*selector)-- == 0)
       return 1;
 
@@ -2912,9 +2924,7 @@
      delete or disable the breakpoint, but the LWP will have already
      tripped on it.  */
 
-  if (lp->waitstatus.kind == TARGET_WAITKIND_IGNORE
-      && lp->status != 0
-      && linux_nat_status_is_event (lp->status)
+  if (linux_nat_lp_status_is_event (lp)
       && cancel_breakpoint (lp))
     /* Throw away the SIGTRAP.  */
     lp->status = 0;
@@ -3433,8 +3443,7 @@
 			 always cancels breakpoint hits in all
 			 threads.  */
 		      if (non_stop
-			  && lp->waitstatus.kind == TARGET_WAITKIND_IGNORE
-			  && linux_nat_status_is_event (lp->status)
+			  && linux_nat_lp_status_is_event (lp)
 			  && cancel_breakpoint (lp))
 			{
 			  /* Throw away the SIGTRAP.  */