http://sourceware.org/ml/gdb-patches/2010-09/msg00361.html

Subject: [patch 4/4]#3 Remove redundant lp->siginfo

Hi,

this is a simplification which should not affect GDB behavior.  As linux-nat

now stops on each received signal without any reordering of them then

PTRACE_GETSIGINFO is enough to access siginfo, without any need to copy it in

advance.

Thanks,

Jan

gdb/

2010-09-20  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* linux-nat.c (resume_callback) <lp->stopped && lp->status == 0>

	(linux_nat_resume): Remove LP->SIGINFO clearing.

	(save_siginfo): Remove.

	(stop_wait_callback) <WSTOPSIG (status) != SIGSTOP>

	(linux_nat_filter_event) <linux_nat_status_is_event (status)>: Remove

	the save_siginfo call.

	(resume_stopped_resumed_lwps): Remove LP->SIGINFO clearing.

	(linux_nat_set_siginfo_fixup): Use PTRACE_GETSIGINFO.

	* linux-nat.h (struct lwp_info) <siginfo>: Remove.

Index: gdb-7.4.50.20111218/gdb/linux-nat.c

===================================================================

--- gdb-7.4.50.20111218.orig/gdb/linux-nat.c	2011-12-19 02:17:05.000000000 +0100

+++ gdb-7.4.50.20111218/gdb/linux-nat.c	2011-12-19 02:17:43.188466854 +0100

@@ -1883,7 +1883,6 @@ resume_lwp (struct lwp_info *lp, int ste

 				step, TARGET_SIGNAL_0);

 	  lp->stopped = 0;

 	  lp->step = step;

-	  memset (&lp->siginfo, 0, sizeof (lp->siginfo));

 	  lp->stopped_by_watchpoint = 0;

 	}

       else

@@ -2027,7 +2026,6 @@ linux_nat_resume (struct target_ops *ops

   if (linux_nat_prepare_to_resume != NULL)

     linux_nat_prepare_to_resume (lp);

   linux_ops->to_resume (linux_ops, ptid, step, signo);

-  memset (&lp->siginfo, 0, sizeof (lp->siginfo));

   lp->stopped_by_watchpoint = 0;

   if (debug_linux_nat)

@@ -2612,22 +2610,6 @@ wait_lwp (struct lwp_info *lp)

   return status;

 }

-/* Save the most recent siginfo for LP.  This is currently only called

-   for SIGTRAP; some ports use the si_addr field for

-   target_stopped_data_address.  In the future, it may also be used to

-   restore the siginfo of requeued signals.  */

-

-static void

-save_siginfo (struct lwp_info *lp)

-{

-  errno = 0;

-  ptrace (PTRACE_GETSIGINFO, GET_LWP (lp->ptid),

-	  (PTRACE_TYPE_ARG3) 0, &lp->siginfo);

-

-  if (errno != 0)

-    memset (&lp->siginfo, 0, sizeof (lp->siginfo));

-}

-

 /* Send a SIGSTOP to LP.  */

 static int

@@ -2872,9 +2854,6 @@ stop_wait_callback (struct lwp_info *lp,

 	{

 	  /* The thread was stopped with a signal other than SIGSTOP.  */

-	  /* Save the trap's siginfo in case we need it later.  */

-	  save_siginfo (lp);

-

 	  save_sigtrap (lp);

 	  if (debug_linux_nat)

@@ -3278,12 +3257,7 @@ linux_nat_filter_event (int lwpid, int s

     }

   if (linux_nat_status_is_event (status))

-    {

-      /* Save the trap's siginfo in case we need it later.  */

-      save_siginfo (lp);

-

-      save_sigtrap (lp);

-    }

+    save_sigtrap (lp);

   /* Check if the thread has exited.  */

   if ((WIFEXITED (status) || WIFSIGNALED (status))

@@ -3961,7 +3935,6 @@ resume_stopped_resumed_lwps (struct lwp_

       linux_ops->to_resume (linux_ops, pid_to_ptid (GET_LWP (lp->ptid)),

 			    lp->step, TARGET_SIGNAL_0);

       lp->stopped = 0;

-      memset (&lp->siginfo, 0, sizeof (lp->siginfo));

       lp->stopped_by_watchpoint = 0;

     }

@@ -6029,11 +6002,19 @@ linux_nat_set_prepare_to_resume (struct

 struct siginfo *

 linux_nat_get_siginfo (ptid_t ptid)

 {

-  struct lwp_info *lp = find_lwp_pid (ptid);

+  static struct siginfo siginfo;

+  int pid;

-  gdb_assert (lp != NULL);

+  pid = GET_LWP (ptid);

+  if (pid == 0)

+    pid = GET_PID (ptid);

+

+  errno = 0;

+  ptrace (PTRACE_GETSIGINFO, pid, (PTRACE_TYPE_ARG3) 0, &siginfo);

+  if (errno != 0)

+    memset (&siginfo, 0, sizeof (siginfo));

-  return &lp->siginfo;

+  return &siginfo;

 }

 /* Provide a prototype to silence -Wmissing-prototypes.  */

Index: gdb-7.4.50.20111218/gdb/linux-nat.h

===================================================================

--- gdb-7.4.50.20111218.orig/gdb/linux-nat.h	2011-12-18 23:40:59.000000000 +0100

+++ gdb-7.4.50.20111218/gdb/linux-nat.h	2011-12-19 02:17:21.355548276 +0100

@@ -77,10 +77,6 @@ struct lwp_info

   /* The kind of stepping of this LWP.  */

   enum resume_step step;

-  /* Non-zero si_signo if this LWP stopped with a trap.  si_addr may

-     be the address of a hardware watchpoint.  */

-  struct siginfo siginfo;

-

   /* STOPPED_BY_WATCHPOINT is non-zero if this LWP stopped with a data

      watchpoint trap.  */

   int stopped_by_watchpoint;