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authorRafael J. Wysocki <rjw@sisk.pl>2007-07-17 07:03:35 -0400
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-07-17 13:23:02 -0400
commit831441862956fffa17b9801db37e6ea1650b0f69 (patch)
treeb0334921341f8f1734bdd3243de76d676329d21c /drivers/block
parent787d2214c19bcc9b6ac48af0ce098277a801eded (diff)
Freezer: make kernel threads nonfreezable by default
Currently, the freezer treats all tasks as freezable, except for the kernel threads that explicitly set the PF_NOFREEZE flag for themselves. This approach is problematic, since it requires every kernel thread to either set PF_NOFREEZE explicitly, or call try_to_freeze(), even if it doesn't care for the freezing of tasks at all. It seems better to only require the kernel threads that want to or need to be frozen to use some freezer-related code and to remove any freezer-related code from the other (nonfreezable) kernel threads, which is done in this patch. The patch causes all kernel threads to be nonfreezable by default (ie. to have PF_NOFREEZE set by default) and introduces the set_freezable() function that should be called by the freezable kernel threads in order to unset PF_NOFREEZE. It also makes all of the currently freezable kernel threads call set_freezable(), so it shouldn't cause any (intentional) change of behaviour to appear. Additionally, it updates documentation to describe the freezing of tasks more accurately. [akpm@linux-foundation.org: build fixes] Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Acked-by: Nigel Cunningham <nigel@nigel.suspend2.net> Cc: Pavel Machek <pavel@ucw.cz> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Gautham R Shenoy <ego@in.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/block')
-rw-r--r--drivers/block/loop.c8
-rw-r--r--drivers/block/pktcdvd.c1
2 files changed, 2 insertions, 7 deletions
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 4503290da407..06eaa11cbc2f 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -68,6 +68,7 @@
68#include <linux/loop.h> 68#include <linux/loop.h>
69#include <linux/compat.h> 69#include <linux/compat.h>
70#include <linux/suspend.h> 70#include <linux/suspend.h>
71#include <linux/freezer.h>
71#include <linux/writeback.h> 72#include <linux/writeback.h>
72#include <linux/buffer_head.h> /* for invalidate_bdev() */ 73#include <linux/buffer_head.h> /* for invalidate_bdev() */
73#include <linux/completion.h> 74#include <linux/completion.h>
@@ -600,13 +601,6 @@ static int loop_thread(void *data)
600 struct loop_device *lo = data; 601 struct loop_device *lo = data;
601 struct bio *bio; 602 struct bio *bio;
602 603
603 /*
604 * loop can be used in an encrypted device,
605 * hence, it mustn't be stopped at all
606 * because it could be indirectly used during suspension
607 */
608 current->flags |= PF_NOFREEZE;
609
610 set_user_nice(current, -20); 604 set_user_nice(current, -20);
611 605
612 while (!kthread_should_stop() || lo->lo_bio) { 606 while (!kthread_should_stop() || lo->lo_bio) {
diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
index 7c294a40002e..31be33e4f119 100644
--- a/drivers/block/pktcdvd.c
+++ b/drivers/block/pktcdvd.c
@@ -1593,6 +1593,7 @@ static int kcdrwd(void *foobar)
1593 long min_sleep_time, residue; 1593 long min_sleep_time, residue;
1594 1594
1595 set_user_nice(current, -20); 1595 set_user_nice(current, -20);
1596 set_freezable();
1596 1597
1597 for (;;) { 1598 for (;;) {
1598 DECLARE_WAITQUEUE(wait, current); 1599 DECLARE_WAITQUEUE(wait, current);