Re: [PATCH 6/6] sched: Change task_struct::state
From: Daniel Thompson <hidden>
Date: 2021-06-07 10:46:19
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On Wed, Jun 02, 2021 at 03:12:31PM +0200, Peter Zijlstra wrote:
quoted hunk ↗ jump to hunk
Change the type and name of task_struct::state. Drop the volatile and shrink it to an 'unsigned int'. Rename it in order to find all uses such that we can use READ_ONCE/WRITE_ONCE as appropriate. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> --- ... kernel/debug/kdb/kdb_support.c | 18 +++++++------ ...--- a/kernel/debug/kdb/kdb_support.c +++ b/kernel/debug/kdb/kdb_support.c@@ -609,23 +609,25 @@ unsigned long kdb_task_state_string(cons */ char kdb_task_state_char (const struct task_struct *p) { - int cpu; - char state; + unsigned int p_state; unsigned long tmp; + char state; + int cpu; if (!p || copy_from_kernel_nofault(&tmp, (char *)p, sizeof(unsigned long))) return 'E'; cpu = kdb_process_cpu(p); - state = (p->state == 0) ? 'R' : - (p->state < 0) ? 'U' : - (p->state & TASK_UNINTERRUPTIBLE) ? 'D' : - (p->state & TASK_STOPPED) ? 'T' : - (p->state & TASK_TRACED) ? 'C' : + p_state = READ_ONCE(p->__state); + state = (p_state == 0) ? 'R' : + (p_state < 0) ? 'U' :
Looks like the U here stands for Unreachable since this patch makes it more obvious that this clause is (and previously was) exactly that! Dropping the U state would be good since I guess this will show up as a "new" warning in some tools. However it was a preexisting problem so with or without this cleaned up: Acked-by: Daniel Thompson <redacted> Daniel.
+ (p_state & TASK_UNINTERRUPTIBLE) ? 'D' :
+ (p_state & TASK_STOPPED) ? 'T' :
+ (p_state & TASK_TRACED) ? 'C' :
(p->exit_state & EXIT_ZOMBIE) ? 'Z' :
(p->exit_state & EXIT_DEAD) ? 'E' :
- (p->state & TASK_INTERRUPTIBLE) ? 'S' : '?';
+ (p_state & TASK_INTERRUPTIBLE) ? 'S' : '?';
if (is_idle_task(p)) {
/* Idle task. Is it really idle, apart from the kdb
* interrupt? */