[PATCH] Make suspend possible with a traced process at a breakpoint

a7ef7878 · Rafael J. Wysocki <[email protected]> · 2006-08-05 12:13:42 -07:00

It should be possible to suspend, either to RAM or to disk, if there's a
traced process that has just reached a breakpoint.  However, this is a
special case, because its parent process might have been frozen already and
then we are unable to deliver the "freeze" signal to the traced process.
If this happens, it's better to cancel the freezing of the traced process.

Ref. http://bugzilla.kernel.org/show_bug.cgi?id=6787

Signed-off-by: Rafael J. Wysocki <[email protected]>
Acked-by: Pavel Machek <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Commit: a7ef7878ea7c8bca9b624db3f61223cdadda2a0a
Parents: f5d635f6

Changes

2 files changed · +26 −8

File	Status	Add	Del	Content
include/linux/sched.h	modified	+8	−0	View file
kernel/power/process.c	modified	+18	−8	View file

include/linux/sched.h

View file

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 6afa72e..6674fc1 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1558,6 +1558,14 @@ static inline void freeze(struct task_struct *p)
 }
 
 /*
+ * Sometimes we may need to cancel the previous 'freeze' request
+ */
+static inline void do_not_freeze(struct task_struct *p)
+{
+	p->flags &= ~PF_FREEZE;
+}
+
+/*
  * Wake up a frozen process
  */
 static inline int thaw_process(struct task_struct *p)

kernel/power/process.c

View file

diff --git a/kernel/power/process.c b/kernel/power/process.c
index b2a5f67..72e72d2 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -66,13 +66,25 @@ static inline void freeze_process(struct task_struct *p)
 	}
 }
 
+static void cancel_freezing(struct task_struct *p)
+{
+	unsigned long flags;
+
+	if (freezing(p)) {
+		pr_debug("  clean up: %s\n", p->comm);
+		do_not_freeze(p);
+		spin_lock_irqsave(&p->sighand->siglock, flags);
+		recalc_sigpending_tsk(p);
+		spin_unlock_irqrestore(&p->sighand->siglock, flags);
+	}
+}
+
 /* 0 = success, else # of processes that we failed to stop */
 int freeze_processes(void)
 {
 	int todo, nr_user, user_frozen;
 	unsigned long start_time;
 	struct task_struct *g, *p;
-	unsigned long flags;
 
 	printk( "Stopping tasks: " );
 	start_time = jiffies;
@@ -85,6 +97,10 @@ int freeze_processes(void)
 				continue;
 			if (frozen(p))
 				continue;
+			if (p->state == TASK_TRACED && frozen(p->parent)) {
+				cancel_freezing(p);
+				continue;
+			}
 			if (p->mm && !(p->flags & PF_BORROWED_MM)) {
 				/* The task is a user-space one.
 				 * Freeze it unless there's a vfork completion
@@ -126,13 +142,7 @@ int freeze_processes(void)
 		do_each_thread(g, p) {
 			if (freezeable(p) && !frozen(p))
 				printk(KERN_ERR "  %s\n", p->comm);
-			if (freezing(p)) {
-				pr_debug("  clean up: %s\n", p->comm);
-				p->flags &= ~PF_FREEZE;
-				spin_lock_irqsave(&p->sighand->siglock, flags);
-				recalc_sigpending_tsk(p);
-				spin_unlock_irqrestore(&p->sighand->siglock, flags);
-			}
+			cancel_freezing(p);
 		} while_each_thread(g, p);
 		read_unlock(&tasklist_lock);
 		return todo;