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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/usb
parent787d2214c19bcc9b6ac48af0ce098277a801eded (diff)
downloadop-kernel-dev-831441862956fffa17b9801db37e6ea1650b0f69.zip
op-kernel-dev-831441862956fffa17b9801db37e6ea1650b0f69.tar.gz
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/usb')
-rw-r--r--drivers/usb/atm/ueagle-atm.c1
-rw-r--r--drivers/usb/core/hub.c1
-rw-r--r--drivers/usb/gadget/file_storage.c3
-rw-r--r--drivers/usb/storage/usb.c3
4 files changed, 6 insertions, 2 deletions
diff --git a/drivers/usb/atm/ueagle-atm.c b/drivers/usb/atm/ueagle-atm.c
index 4973e14..8f04665 100644
--- a/drivers/usb/atm/ueagle-atm.c
+++ b/drivers/usb/atm/ueagle-atm.c
@@ -1168,6 +1168,7 @@ static int uea_kthread(void *data)
struct uea_softc *sc = data;
int ret = -EAGAIN;
+ set_freezable();
uea_enters(INS_TO_USBDEV(sc));
while (!kthread_should_stop()) {
if (ret < 0 || sc->reset)
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 50e79010..fd74c50 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -2728,6 +2728,7 @@ loop:
static int hub_thread(void *__unused)
{
+ set_freezable();
do {
hub_events();
wait_event_interruptible(khubd_wait,
diff --git a/drivers/usb/gadget/file_storage.c b/drivers/usb/gadget/file_storage.c
index 8712ef9..be7a1bd 100644
--- a/drivers/usb/gadget/file_storage.c
+++ b/drivers/usb/gadget/file_storage.c
@@ -3434,6 +3434,9 @@ static int fsg_main_thread(void *fsg_)
allow_signal(SIGKILL);
allow_signal(SIGUSR1);
+ /* Allow the thread to be frozen */
+ set_freezable();
+
/* Arrange for userspace references to be interpreted as kernel
* pointers. That way we can pass a kernel pointer to a routine
* that expects a __user pointer and it will work okay. */
diff --git a/drivers/usb/storage/usb.c b/drivers/usb/storage/usb.c
index bef8bcd..28842d2 100644
--- a/drivers/usb/storage/usb.c
+++ b/drivers/usb/storage/usb.c
@@ -311,8 +311,6 @@ static int usb_stor_control_thread(void * __us)
struct Scsi_Host *host = us_to_host(us);
int autopm_rc;
- current->flags |= PF_NOFREEZE;
-
for(;;) {
US_DEBUGP("*** thread sleeping.\n");
if(down_interruptible(&us->sema))
@@ -920,6 +918,7 @@ static int usb_stor_scan_thread(void * __us)
printk(KERN_DEBUG
"usb-storage: device found at %d\n", us->pusb_dev->devnum);
+ set_freezable();
/* Wait for the timeout to expire or for a disconnect */
if (delay_use > 0) {
printk(KERN_DEBUG "usb-storage: waiting for device "
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