Currently, to tell a task that it should go to the refrigerator, we set the
PF_FREEZE flag for it and send a fake signal to it. Unfortunately there
are two SMP-related problems with this approach. First, a task running on
another CPU may be updating its flags while the freezer attempts to set
PF_FREEZE for it and this may leave the task's flags in an inconsistent
state. Second, there is a potential race between freeze_process() and
refrigerator() in which freeze_process() running on one CPU is reading a
task's PF_FREEZE flag while refrigerator() running on another CPU has just
set PF_FROZEN for the same task and attempts to reset PF_FREEZE for it. If
the refrigerator wins the race, freeze_process() will state that PF_FREEZE
hasn't been set for the task and will set it unnecessarily, so the task
will go to the refrigerator once again after it's been thawed.
To solve first of these problems we need to stop using PF_FREEZE to tell
tasks that they should go to the refrigerator. Instead, we can introduce a
special TIF_*** flag and use it for this purpose, since it is allowed to
change the other tasks' TIF_*** flags and there are special calls for it.
To avoid the freeze_process()-refrigerator() race we can make
freeze_process() to always check the task's PF_FROZEN flag after it's read
its "freeze" flag. We should also make sure that refrigerator() will
always reset the task's "freeze" flag after it's set PF_FROZEN for it.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: David Howells <dhowells@redhat.com>
Cc: Andi Kleen <ak@muc.de>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
There were a number of places that made evil PAGE_SIZE == 4k
assumptions that ended up breaking when trying to play with
8k and 64k page sizes, this fixes those up.
The most significant change is the way we load THREAD_SIZE,
previously this was done via:
mov #(THREAD_SIZE >> 8), reg
shll8 reg
to avoid a memory access and allow the immediate load. With
a 64k PAGE_SIZE, we're out of range for the immediate load
size without resorting to special instructions available in
later ISAs (movi20s and so on). The "workaround" for this is
to bump up the shift to 10 and insert a shll2, which gives a
bit more flexibility while still being much cheaper than a
memory access.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
This enables support for 4K stacks on SH.
Currently this depends on DEBUG_KERNEL, but likely all boards
will switch to this as the default in the future.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Drop TIF_USERSPACE and add addr_limit to the thread_info struct.
Subsequently, use that for address checking in strnlen_user() to
ward off bogus -EFAULTs.
Make __strnlen_user() return 0 on exception, rather than -EFAULT.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Initial register bank cleanup. Make SR.RB configurable, and add some
preliminary documentation on register bank usage within the kernel.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
The test_bit() routines are defined to work on a pointer to unsigned long.
But thread_info.flags is __u32 (unsigned int) on sh and it is passed to flag
set/clear/test wrappers in include/linux/thread_info.h. So the compiler will
print warnings.
This patch changes to unsigned long instead.
Signed-off-by: Akinobu Mita <mita@miraclelinux.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Kazumoto Kojima <kkojima@rr.iij4u.or.jp>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
{get,put}_thread_info() were introduced in 2.5.4 and never
had been called by anything in the tree.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The preempt_count member of struct thread_info is currently either defined
as int, unsigned int or __s32 depending on arch. This patch makes the type
of preempt_count an int on all archs.
Having preempt_count be an unsigned type prevents the catching of
preempt_count < 0 bugs, and using int on some archs and __s32 on others is
not exactely "neat" - much nicer when it's just int all over.
A previous version of this patch was already ACK'ed by Robert Love, and the
only change in this version of the patch compared to the one he ACK'ed is
that this one also makes sure the preempt_count member is consistently
commented.
Signed-off-by: Jesper Juhl <juhl-lkml@dif.dk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Port Paulus's ppc64 fix to sh:
When the generic IRQ stuff went in, it seems that HARDIRQ_BITS got bumped
from 9 (for ppc64) up to 12. Consequently, the PREEMPT_ACTIVE bit is now
within HARDIRQ_MASK, and I get in_interrupt() falsely returning true when
PREEMPT_ACTIVE is set, and thus a BUG_ON tripping in arch/ppc64/mm/tlb.c.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Rafael J. Wysocki