perf: Drop unappropriate tests on arch callchains

Drop the TASK_RUNNING test on user tasks for callchains as
this check doesn't seem to make any sense.

Also remove the tests for !current that is not supposed to
happen and current->pid as this should be handled at the
generic level, with exclude_idle attribute.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Tested-by: Will Deacon <will.deacon@arm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: David Miller <davem@davemloft.net>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Borislav Petkov <bp@amd64.org>

arch/arm/kernel/perf_event.c

@@ -3107,12 +3107,6 @@ perf_do_callchain(struct pt_regs *regs,
 
 	is_user = user_mode(regs);
 
-	if (!current || !current->pid)
-		return;
-
-	if (is_user && current->state != TASK_RUNNING)
-		return;
-
 	if (!is_user)
 		perf_callchain_kernel(regs, entry);
 

arch/sh/kernel/perf_callchain.c

@@ -68,9 +68,6 @@ perf_do_callchain(struct pt_regs *regs, struct perf_callchain_entry *entry)
 
 	is_user = user_mode(regs);
 
-	if (is_user && current->state != TASK_RUNNING)
-		return;
-
 	/*
 	 * Only the kernel side is implemented for now.
 	 */

arch/x86/kernel/cpu/perf_event.c

@@ -1703,9 +1703,6 @@ perf_do_callchain(struct pt_regs *regs, struct perf_callchain_entry *entry)
 
 	is_user = user_mode(regs);
 
-	if (is_user && current->state != TASK_RUNNING)
-		return;
-
 	if (!is_user)
 		perf_callchain_kernel(regs, entry);