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authorRafael J. Wysocki <rjw@sisk.pl>2007-07-17 04:03:35 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-07-17 10:23:02 -0700
commit831441862956fffa17b9801db37e6ea1650b0f69 (patch)
treeb0334921341f8f1734bdd3243de76d676329d21c /drivers/scsi
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/scsi')
-rw-r--r--drivers/scsi/libsas/sas_scsi_host.c3
-rw-r--r--drivers/scsi/scsi_error.c3
2 files changed, 2 insertions, 4 deletions
diff --git a/drivers/scsi/libsas/sas_scsi_host.c b/drivers/scsi/libsas/sas_scsi_host.c
index d70ddfda93f..9c5342e7a69 100644
--- a/drivers/scsi/libsas/sas_scsi_host.c
+++ b/drivers/scsi/libsas/sas_scsi_host.c
@@ -40,6 +40,7 @@
#include <linux/err.h>
#include <linux/blkdev.h>
+#include <linux/freezer.h>
#include <linux/scatterlist.h>
/* ---------- SCSI Host glue ---------- */
@@ -868,8 +869,6 @@ static int sas_queue_thread(void *_sas_ha)
{
struct sas_ha_struct *sas_ha = _sas_ha;
- current->flags |= PF_NOFREEZE;
-
while (1) {
set_current_state(TASK_INTERRUPTIBLE);
schedule();
diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 9adb64ac054..8a525abda30 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -19,6 +19,7 @@
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/kernel.h>
+#include <linux/freezer.h>
#include <linux/kthread.h>
#include <linux/interrupt.h>
#include <linux/blkdev.h>
@@ -1516,8 +1517,6 @@ int scsi_error_handler(void *data)
{
struct Scsi_Host *shost = data;
- current->flags |= PF_NOFREEZE;
-
/*
* We use TASK_INTERRUPTIBLE so that the thread is not
* counted against the load average as a running process.