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authorRafael J. Wysocki <rjw@sisk.pl>2007-05-23 13:57:25 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-05-23 20:14:11 -0700
commitba96a0c88098697a63e80157718b7440414ed24d (patch)
treebdd999761eed452cc162f5b63166d1014aaf2e3e /kernel
parent33e1c288da62a6a5aa9077a6b7bfa690b1b02cf4 (diff)
downloadop-kernel-dev-ba96a0c88098697a63e80157718b7440414ed24d.zip
op-kernel-dev-ba96a0c88098697a63e80157718b7440414ed24d.tar.gz
freezer: fix vfork problem
Currently try_to_freeze_tasks() has to wait until all of the vforked processes exit and for this reason every user can make it fail. To fix this problem we can introduce the additional process flag PF_FREEZER_SKIP to be used by tasks that do not want to be counted as freezable by the freezer and want to have TIF_FREEZE set nevertheless. Then, this flag can be set by tasks using sys_vfork() before they call wait_for_completion(&vfork) and cleared after they have woken up. After clearing it, the tasks should call try_to_freeze() as soon as possible. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Cc: Gautham R Shenoy <ego@in.ibm.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Pavel Machek <pavel@ucw.cz> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/fork.c3
-rw-r--r--kernel/power/process.c29
2 files changed, 12 insertions, 20 deletions
diff --git a/kernel/fork.c b/kernel/fork.c
index 87069cf..73ad5cd 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -45,6 +45,7 @@
#include <linux/acct.h>
#include <linux/tsacct_kern.h>
#include <linux/cn_proc.h>
+#include <linux/freezer.h>
#include <linux/delayacct.h>
#include <linux/taskstats_kern.h>
#include <linux/random.h>
@@ -1405,7 +1406,9 @@ long do_fork(unsigned long clone_flags,
}
if (clone_flags & CLONE_VFORK) {
+ freezer_do_not_count();
wait_for_completion(&vfork);
+ freezer_count();
if (unlikely (current->ptrace & PT_TRACE_VFORK_DONE)) {
current->ptrace_message = nr;
ptrace_notify ((PTRACE_EVENT_VFORK_DONE << 8) | SIGTRAP);
diff --git a/kernel/power/process.c b/kernel/power/process.c
index 02e490e..eefca85 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -120,22 +120,12 @@ static unsigned int try_to_freeze_tasks(int freeze_user_space)
cancel_freezing(p);
continue;
}
- if (is_user_space(p)) {
- if (!freeze_user_space)
- continue;
-
- /* Freeze the task unless there is a vfork
- * completion pending
- */
- if (!p->vfork_done)
- freeze_process(p);
- } else {
- if (freeze_user_space)
- continue;
-
- freeze_process(p);
- }
- todo++;
+ if (is_user_space(p) == !freeze_user_space)
+ continue;
+
+ freeze_process(p);
+ if (!freezer_should_skip(p))
+ todo++;
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
yield(); /* Yield is okay here */
@@ -161,7 +151,8 @@ static unsigned int try_to_freeze_tasks(int freeze_user_space)
continue;
task_lock(p);
- if (freezeable(p) && !frozen(p))
+ if (freezeable(p) && !frozen(p) &&
+ !freezer_should_skip(p))
printk(KERN_ERR " %s\n", p->comm);
cancel_freezing(p);
@@ -210,9 +201,7 @@ static void thaw_tasks(int thaw_user_space)
if (is_user_space(p) == !thaw_user_space)
continue;
- if (!thaw_process(p))
- printk(KERN_WARNING " Strange, %s not stopped\n",
- p->comm );
+ thaw_process(p);
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
}
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