kdb: Adopt scheduler's task classification

Currently kdb contains some open-coded routines to generate a summary
character for each task. This code currently issues warnings, is
almost certainly broken and won't make sense to any kernel dev who
has ever used /proc to examine task states.

Fix both the warning and the potential for confusion by adopting the
scheduler's task classification. Whilst doing this we also simplify the
filtering by using mask strings directly (which means we don't have to
guess all the characters the scheduler might give us).

Unfortunately we can't quite match the scheduler classification completely.
We add four extra states: - for idle loops and i, m and s for sleeping
system daemons (which means kthreads in one of the I, M and S states).
These extra states are used to manage the filters for tools to make the
output of ps and bta less noisy.

Note: The Fixes below is the last point the original dubious code was
      moved; it was not introduced by that patch. However it gives us
      the last point to which this patch can be easily backported.
      Happily that should be enough to cover the introduction of
      CONFIG_WERROR!

Fixes: 2f064a59a11f ("sched: Change task_struct::state")
Link: https://lore.kernel.org/r/20211102173158.3315227-1-daniel.thompson@linaro.org
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>

1 files changed, 8 insertions, 8 deletions

diff --git a/kernel/debug/kdb/kdb_bt.c b/kernel/debug/kdb/kdb_bt.c
index 1f9f0e47aeda..10b454554ab0 100644
--- a/kernel/debug/kdb/kdb_bt.c
+++ b/kernel/debug/kdb/kdb_bt.c
@@ -46,7 +46,7 @@ static void kdb_show_stack(struct task_struct *p, void *addr)
  *	btp <pid>			Kernel stack for <pid>
  *	btt <address-expression>	Kernel stack for task structure at
  *					<address-expression>
- *	bta [DRSTCZEUIMA]		All useful processes, optionally
+ *	bta [state_chars>|A]		All useful processes, optionally
  *					filtered by state
  *	btc [<cpu>]			The current process on one cpu,
  *					default is all cpus
@@ -74,7 +74,7 @@ static void kdb_show_stack(struct task_struct *p, void *addr)
  */
 
 static int
-kdb_bt1(struct task_struct *p, unsigned long mask, bool btaprompt)
+kdb_bt1(struct task_struct *p, const char *mask, bool btaprompt)
 {
 	char ch;
 
@@ -120,7 +120,7 @@ kdb_bt_cpu(unsigned long cpu)
 		return;
 	}
 
-	kdb_bt1(kdb_tsk, ~0UL, false);
+	kdb_bt1(kdb_tsk, "A", false);
 }
 
 int
@@ -138,8 +138,8 @@ kdb_bt(int argc, const char **argv)
 	if (strcmp(argv[0], "bta") == 0) {
 		struct task_struct *g, *p;
 		unsigned long cpu;
-		unsigned long mask = kdb_task_state_string(argc ? argv[1] :
-							   NULL);
+		const char *mask = argc ? argv[1] : kdbgetenv("PS");
+
 		if (argc == 0)
 			kdb_ps_suppressed();
 		/* Run the active tasks first */
@@ -167,7 +167,7 @@ kdb_bt(int argc, const char **argv)
 			return diag;
 		p = find_task_by_pid_ns(pid, &init_pid_ns);
 		if (p)
-			return kdb_bt1(p, ~0UL, false);
+			return kdb_bt1(p, "A", false);
 		kdb_printf("No process with pid == %ld found\n", pid);
 		return 0;
 	} else if (strcmp(argv[0], "btt") == 0) {
@@ -176,7 +176,7 @@ kdb_bt(int argc, const char **argv)
 		diag = kdbgetularg((char *)argv[1], &addr);
 		if (diag)
 			return diag;
-		return kdb_bt1((struct task_struct *)addr, ~0UL, false);
+		return kdb_bt1((struct task_struct *)addr, "A", false);
 	} else if (strcmp(argv[0], "btc") == 0) {
 		unsigned long cpu = ~0;
 		if (argc > 1)
@@ -212,7 +212,7 @@ kdb_bt(int argc, const char **argv)
 			kdb_show_stack(kdb_current_task, (void *)addr);
 			return 0;
 		} else {
-			return kdb_bt1(kdb_current_task, ~0UL, false);
+			return kdb_bt1(kdb_current_task, "A", false);
 		}
 	}