ptrace/x86: simplify the "disable" logic in ptrace_write_dr7()

ptrace_write_dr7() looks unnecessarily overcomplicated.  We can factor
out ptrace_modify_breakpoint() and do not do "continue" twice, just we
need to pass the proper "disabled" argument to
ptrace_modify_breakpoint().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jan Kratochvil <jan.kratochvil@redhat.com>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Prasad <prasad@linux.vnet.ibm.com>
Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 15 insertions, 25 deletions

diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 7a98b21945aa..0649f166d7c6 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -637,9 +637,7 @@ static int ptrace_write_dr7(struct task_struct *tsk, unsigned long data)
         struct thread_struct *thread = &(tsk->thread);
         unsigned long old_dr7;
         int i, orig_ret = 0, rc = 0;
-        int enabled, second_pass = 0;
-        unsigned len, type;
-        struct perf_event *bp;
+        int second_pass = 0;
 
         data &= ~DR_CONTROL_RESERVED;
         old_dr7 = ptrace_get_dr7(thread->ptrace_bps);
@@ -649,30 +647,22 @@ restore:
          * appropriate changes to each.
          */
         for (i = 0; i < HBP_NUM; i++) {
-                enabled = decode_dr7(data, i, &len, &type);
-                bp = thread->ptrace_bps[i];
-
-                if (!enabled) {
-                        if (bp) {
-                                /*
-                                 * Don't unregister the breakpoints right-away,
-                                 * unless all register_user_hw_breakpoint()
-                                 * requests have succeeded. This prevents
-                                 * any window of opportunity for debug
-                                 * register grabbing by other users.
-                                 */
-                                if (!second_pass)
-                                        continue;
-
-                                rc = ptrace_modify_breakpoint(bp, len, type,
-                                                              tsk, 1);
-                                if (rc)
-                                        break;
-                        }
-                        continue;
+                unsigned len, type;
+                bool disabled = !decode_dr7(data, i, &len, &type);
+                struct perf_event *bp = thread->ptrace_bps[i];
+
+                if (disabled) {
+                        /*
+                         * Don't unregister the breakpoints right-away, unless
+                         * all register_user_hw_breakpoint() requests have
+                         * succeeded. This prevents any window of opportunity
+                         * for debug register grabbing by other users.
+                         */
+                        if (!bp || !second_pass)
+                                continue;
                 }
 
-                rc = ptrace_modify_breakpoint(bp, len, type, tsk, 0);
+                rc = ptrace_modify_breakpoint(bp, len, type, tsk, disabled);
                 if (rc)
                         break;
         }