Re: [PATCH] uprobes: Improve scalability by reducing the contention on siglock

From
Oleg Nesterov <oleg@redhat.com>
Date
2024-08-01 14:06:56
Also in
linux-perf-users, lkml
Reply to
Liao Chang, 2024-08-01
On 08/01, Liao Chang wrote:
quoted hunk ↗ jump to hunk
@@ -2276,22 +2277,25 @@ static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs)
 	int err = 0;
 
 	uprobe = utask->active_uprobe;
-	if (utask->state == UTASK_SSTEP_ACK)
+	switch (utask->state) {
+	case UTASK_SSTEP_ACK:
 		err = arch_uprobe_post_xol(&uprobe->arch, regs);
-	else if (utask->state == UTASK_SSTEP_TRAPPED)
+		break;
+	case UTASK_SSTEP_TRAPPED:
 		arch_uprobe_abort_xol(&uprobe->arch, regs);
-	else
+		fallthrough;
+	case UTASK_SSTEP_DENY_SIGNAL:
+		set_tsk_thread_flag(current, TIF_SIGPENDING);
+		break;
+	default:
 		WARN_ON_ONCE(1);
+	}
Liao, at first glance this change looks "obviously wrong" to me.

But let me read this patch more carefully and reply on weekend,
I am a bit busy right now.

Thanks,

Oleg.
Thread (11 messages) 11 messages, 2 authors, last reply 2024-08-08
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