ptrace: kill trivial tracehooks

At this point, tracehooks aren't useful to mainline kernel and mostly
just add an extra layer of obfuscation.  Although they have comments,
without actual in-kernel users, it is difficult to tell what are their
assumptions and they're actually trying to achieve.  To mainline
kernel, they just aren't worth keeping around.

This patch kills the following trivial tracehooks.

* Ones testing whether task is ptraced.  Replace with ->ptrace test.

	tracehook_expect_breakpoints()
	tracehook_consider_ignored_signal()
	tracehook_consider_fatal_signal()

* ptrace_event() wrappers.  Call directly.

	tracehook_report_exec()
	tracehook_report_exit()
	tracehook_report_vfork_done()

* ptrace_release_task() wrapper.  Call directly.

	tracehook_finish_release_task()

* noop

	tracehook_prepare_release_task()
	tracehook_report_death()

This doesn't introduce any behavior change.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/arch/s390/kernel/traps.c b/arch/s390/kernel/traps.c
index a65d2e82f61..a63d34c3611 100644
--- a/arch/s390/kernel/traps.c
+++ b/arch/s390/kernel/traps.c
@@ -331,7 +331,7 @@ void __kprobes do_per_trap(struct pt_regs *regs)
 {
         if (notify_die(DIE_SSTEP, "sstep", regs, 0, 0, SIGTRAP) == NOTIFY_STOP)
                 return;
-        if (tracehook_consider_fatal_signal(current, SIGTRAP))
+        if (current->ptrace)
                 force_sig(SIGTRAP, current);
 }
 
@@ -425,7 +425,7 @@ static void __kprobes illegal_op(struct pt_regs *regs, long pgm_int_code,
                 if (get_user(*((__u16 *) opcode), (__u16 __user *) location))
                         return;
                 if (*((__u16 *) opcode) == S390_BREAKPOINT_U16) {
-                        if (tracehook_consider_fatal_signal(current, SIGTRAP))
+                        if (current->ptrace)
                                 force_sig(SIGTRAP, current);
                         else
                                 signal = SIGILL;