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Merge branch 'master' of /home/davem/src/GIT/linux-2.6/
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David S. Miller committed Apr 21, 2010
2 parents 6651ffc + 05ce7bf commit e04997b
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39 changes: 22 additions & 17 deletions Documentation/RCU/NMI-RCU.txt
Original file line number Diff line number Diff line change
Expand Up @@ -34,7 +34,7 @@ NMI handler.
cpu = smp_processor_id();
++nmi_count(cpu);

if (!rcu_dereference(nmi_callback)(regs, cpu))
if (!rcu_dereference_sched(nmi_callback)(regs, cpu))
default_do_nmi(regs);

nmi_exit();
Expand All @@ -47,12 +47,13 @@ function pointer. If this handler returns zero, do_nmi() invokes the
default_do_nmi() function to handle a machine-specific NMI. Finally,
preemption is restored.

Strictly speaking, rcu_dereference() is not needed, since this code runs
only on i386, which does not need rcu_dereference() anyway. However,
it is a good documentation aid, particularly for anyone attempting to
do something similar on Alpha.
In theory, rcu_dereference_sched() is not needed, since this code runs
only on i386, which in theory does not need rcu_dereference_sched()
anyway. However, in practice it is a good documentation aid, particularly
for anyone attempting to do something similar on Alpha or on systems
with aggressive optimizing compilers.

Quick Quiz: Why might the rcu_dereference() be necessary on Alpha,
Quick Quiz: Why might the rcu_dereference_sched() be necessary on Alpha,
given that the code referenced by the pointer is read-only?


Expand Down Expand Up @@ -99,17 +100,21 @@ invoke irq_enter() and irq_exit() on NMI entry and exit, respectively.

Answer to Quick Quiz

Why might the rcu_dereference() be necessary on Alpha, given
Why might the rcu_dereference_sched() be necessary on Alpha, given
that the code referenced by the pointer is read-only?

Answer: The caller to set_nmi_callback() might well have
initialized some data that is to be used by the
new NMI handler. In this case, the rcu_dereference()
would be needed, because otherwise a CPU that received
an NMI just after the new handler was set might see
the pointer to the new NMI handler, but the old
pre-initialized version of the handler's data.

More important, the rcu_dereference() makes it clear
to someone reading the code that the pointer is being
protected by RCU.
initialized some data that is to be used by the new NMI
handler. In this case, the rcu_dereference_sched() would
be needed, because otherwise a CPU that received an NMI
just after the new handler was set might see the pointer
to the new NMI handler, but the old pre-initialized
version of the handler's data.

This same sad story can happen on other CPUs when using
a compiler with aggressive pointer-value speculation
optimizations.

More important, the rcu_dereference_sched() makes it
clear to someone reading the code that the pointer is
being protected by RCU-sched.
7 changes: 4 additions & 3 deletions Documentation/RCU/checklist.txt
Original file line number Diff line number Diff line change
Expand Up @@ -260,7 +260,8 @@ over a rather long period of time, but improvements are always welcome!
The reason that it is permissible to use RCU list-traversal
primitives when the update-side lock is held is that doing so
can be quite helpful in reducing code bloat when common code is
shared between readers and updaters.
shared between readers and updaters. Additional primitives
are provided for this case, as discussed in lockdep.txt.

10. Conversely, if you are in an RCU read-side critical section,
and you don't hold the appropriate update-side lock, you -must-
Expand Down Expand Up @@ -344,8 +345,8 @@ over a rather long period of time, but improvements are always welcome!
requiring SRCU's read-side deadlock immunity or low read-side
realtime latency.

Note that, rcu_assign_pointer() and rcu_dereference() relate to
SRCU just as they do to other forms of RCU.
Note that, rcu_assign_pointer() relates to SRCU just as they do
to other forms of RCU.

15. The whole point of call_rcu(), synchronize_rcu(), and friends
is to wait until all pre-existing readers have finished before
Expand Down
28 changes: 26 additions & 2 deletions Documentation/RCU/lockdep.txt
Original file line number Diff line number Diff line change
Expand Up @@ -32,9 +32,20 @@ checking of rcu_dereference() primitives:
srcu_dereference(p, sp):
Check for SRCU read-side critical section.
rcu_dereference_check(p, c):
Use explicit check expression "c".
Use explicit check expression "c". This is useful in
code that is invoked by both readers and updaters.
rcu_dereference_raw(p)
Don't check. (Use sparingly, if at all.)
rcu_dereference_protected(p, c):
Use explicit check expression "c", and omit all barriers
and compiler constraints. This is useful when the data
structure cannot change, for example, in code that is
invoked only by updaters.
rcu_access_pointer(p):
Return the value of the pointer and omit all barriers,
but retain the compiler constraints that prevent duplicating
or coalescsing. This is useful when when testing the
value of the pointer itself, for example, against NULL.

The rcu_dereference_check() check expression can be any boolean
expression, but would normally include one of the rcu_read_lock_held()
Expand All @@ -59,7 +70,20 @@ In case (1), the pointer is picked up in an RCU-safe manner for vanilla
RCU read-side critical sections, in case (2) the ->file_lock prevents
any change from taking place, and finally, in case (3) the current task
is the only task accessing the file_struct, again preventing any change
from taking place.
from taking place. If the above statement was invoked only from updater
code, it could instead be written as follows:

file = rcu_dereference_protected(fdt->fd[fd],
lockdep_is_held(&files->file_lock) ||
atomic_read(&files->count) == 1);

This would verify cases #2 and #3 above, and furthermore lockdep would
complain if this was used in an RCU read-side critical section unless one
of these two cases held. Because rcu_dereference_protected() omits all
barriers and compiler constraints, it generates better code than do the
other flavors of rcu_dereference(). On the other hand, it is illegal
to use rcu_dereference_protected() if either the RCU-protected pointer
or the RCU-protected data that it points to can change concurrently.

There are currently only "universal" versions of the rcu_assign_pointer()
and RCU list-/tree-traversal primitives, which do not (yet) check for
Expand Down
6 changes: 6 additions & 0 deletions Documentation/RCU/whatisRCU.txt
Original file line number Diff line number Diff line change
Expand Up @@ -840,6 +840,12 @@ SRCU: Initialization/cleanup
init_srcu_struct
cleanup_srcu_struct

All: lockdep-checked RCU-protected pointer access

rcu_dereference_check
rcu_dereference_protected
rcu_access_pointer

See the comment headers in the source code (or the docbook generated
from them) for more information.

Expand Down
23 changes: 17 additions & 6 deletions Documentation/input/multi-touch-protocol.txt
Original file line number Diff line number Diff line change
Expand Up @@ -68,6 +68,22 @@ like:
SYN_MT_REPORT
SYN_REPORT

Here is the sequence after lifting one of the fingers:

ABS_MT_POSITION_X
ABS_MT_POSITION_Y
SYN_MT_REPORT
SYN_REPORT

And here is the sequence after lifting the remaining finger:

SYN_MT_REPORT
SYN_REPORT

If the driver reports one of BTN_TOUCH or ABS_PRESSURE in addition to the
ABS_MT events, the last SYN_MT_REPORT event may be omitted. Otherwise, the
last SYN_REPORT will be dropped by the input core, resulting in no
zero-finger event reaching userland.

Event Semantics
---------------
Expand Down Expand Up @@ -217,11 +233,6 @@ where examples can be found.
difference between the contact position and the approaching tool position
could be used to derive tilt.
[2] The list can of course be extended.
[3] The multi-touch X driver is currently in the prototyping stage. At the
time of writing (April 2009), the MT protocol is not yet merged, and the
prototype implements finger matching, basic mouse support and two-finger
scrolling. The project aims at improving the quality of current multi-touch
functionality available in the Synaptics X driver, and in addition
implement more advanced gestures.
[3] Multitouch X driver project: http://bitmath.org/code/multitouch/.
[4] See the section on event computation.
[5] See the section on finger tracking.
5 changes: 0 additions & 5 deletions Documentation/kernel-parameters.txt
Original file line number Diff line number Diff line change
Expand Up @@ -320,11 +320,6 @@ and is between 256 and 4096 characters. It is defined in the file
amd_iommu= [HW,X86-84]
Pass parameters to the AMD IOMMU driver in the system.
Possible values are:
isolate - enable device isolation (each device, as far
as possible, will get its own protection
domain) [default]
share - put every device behind one IOMMU into the
same protection domain
fullflush - enable flushing of IO/TLB entries when
they are unmapped. Otherwise they are
flushed before they will be reused, which
Expand Down
14 changes: 12 additions & 2 deletions MAINTAINERS
Original file line number Diff line number Diff line change
Expand Up @@ -485,8 +485,8 @@ S: Maintained
F: drivers/input/mouse/bcm5974.c

APPLE SMC DRIVER
M: Nicolas Boichat <nicolas@boichat.ch>
L: mactel-linux-devel@lists.sourceforge.net
M: Henrik Rydberg <rydberg@euromail.se>
L: lm-sensors@lm-sensors.org
S: Maintained
F: drivers/hwmon/applesmc.c

Expand Down Expand Up @@ -971,6 +971,16 @@ L: linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
W: http://www.mcuos.com
S: Maintained

ARM/U300 MACHINE SUPPORT
M: Linus Walleij <linus.walleij@stericsson.com>
L: linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
S: Supported
F: arch/arm/mach-u300/
F: drivers/i2c/busses/i2c-stu300.c
F: drivers/rtc/rtc-coh901331.c
F: drivers/watchdog/coh901327_wdt.c
F: drivers/dma/coh901318*

ARM/U8500 ARM ARCHITECTURE
M: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com>
L: linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
Expand Down
4 changes: 2 additions & 2 deletions Makefile
Original file line number Diff line number Diff line change
@@ -1,8 +1,8 @@
VERSION = 2
PATCHLEVEL = 6
SUBLEVEL = 34
EXTRAVERSION = -rc3
NAME = Man-Eating Seals of Antiquity
EXTRAVERSION = -rc5
NAME = Sheep on Meth

# *DOCUMENTATION*
# To see a list of typical targets execute "make help"
Expand Down
2 changes: 1 addition & 1 deletion arch/arm/boot/compressed/head.S
Original file line number Diff line number Diff line change
Expand Up @@ -172,7 +172,7 @@ not_angel:
adr r0, LC0
ARM( ldmia r0, {r1, r2, r3, r4, r5, r6, r11, ip, sp})
THUMB( ldmia r0, {r1, r2, r3, r4, r5, r6, r11, ip} )
THUMB( ldr sp, [r0, #28] )
THUMB( ldr sp, [r0, #32] )
subs r0, r0, r1 @ calculate the delta offset

@ if delta is zero, we are
Expand Down
15 changes: 14 additions & 1 deletion arch/arm/include/asm/highmem.h
Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,11 @@

#define kmap_prot PAGE_KERNEL

#define flush_cache_kmaps() flush_cache_all()
#define flush_cache_kmaps() \
do { \
if (cache_is_vivt()) \
flush_cache_all(); \
} while (0)

extern pte_t *pkmap_page_table;

Expand All @@ -21,11 +25,20 @@ extern void *kmap_high(struct page *page);
extern void *kmap_high_get(struct page *page);
extern void kunmap_high(struct page *page);

extern void *kmap_high_l1_vipt(struct page *page, pte_t *saved_pte);
extern void kunmap_high_l1_vipt(struct page *page, pte_t saved_pte);

/*
* The following functions are already defined by <linux/highmem.h>
* when CONFIG_HIGHMEM is not set.
*/
#ifdef CONFIG_HIGHMEM
extern void *kmap(struct page *page);
extern void kunmap(struct page *page);
extern void *kmap_atomic(struct page *page, enum km_type type);
extern void kunmap_atomic(void *kvaddr, enum km_type type);
extern void *kmap_atomic_pfn(unsigned long pfn, enum km_type type);
extern struct page *kmap_atomic_to_page(const void *ptr);
#endif

#endif
1 change: 1 addition & 0 deletions arch/arm/include/asm/kmap_types.h
Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,7 @@ enum km_type {
KM_IRQ1,
KM_SOFTIRQ0,
KM_SOFTIRQ1,
KM_L1_CACHE,
KM_L2_CACHE,
KM_TYPE_NR
};
Expand Down
23 changes: 11 additions & 12 deletions arch/arm/include/asm/ucontext.h
Original file line number Diff line number Diff line change
Expand Up @@ -59,23 +59,22 @@ struct iwmmxt_sigframe {
#endif /* CONFIG_IWMMXT */

#ifdef CONFIG_VFP
#if __LINUX_ARM_ARCH__ < 6
/* For ARM pre-v6, we use fstmiax and fldmiax. This adds one extra
* word after the registers, and a word of padding at the end for
* alignment. */
#define VFP_MAGIC 0x56465001
#define VFP_STORAGE_SIZE 152
#else
#define VFP_MAGIC 0x56465002
#define VFP_STORAGE_SIZE 144
#endif

struct vfp_sigframe
{
unsigned long magic;
unsigned long size;
union vfp_state storage;
};
struct user_vfp ufp;
struct user_vfp_exc ufp_exc;
} __attribute__((__aligned__(8)));

/*
* 8 byte for magic and size, 264 byte for ufp, 12 bytes for ufp_exc,
* 4 bytes padding.
*/
#define VFP_STORAGE_SIZE sizeof(struct vfp_sigframe)

#endif /* CONFIG_VFP */

/*
Expand All @@ -91,7 +90,7 @@ struct aux_sigframe {
#ifdef CONFIG_IWMMXT
struct iwmmxt_sigframe iwmmxt;
#endif
#if 0 && defined CONFIG_VFP /* Not yet saved. */
#ifdef CONFIG_VFP
struct vfp_sigframe vfp;
#endif
/* Something that isn't a valid magic number for any coprocessor. */
Expand Down
12 changes: 11 additions & 1 deletion arch/arm/include/asm/user.h
Original file line number Diff line number Diff line change
Expand Up @@ -83,11 +83,21 @@ struct user{

/*
* User specific VFP registers. If only VFPv2 is present, registers 16 to 31
* are ignored by the ptrace system call.
* are ignored by the ptrace system call and the signal handler.
*/
struct user_vfp {
unsigned long long fpregs[32];
unsigned long fpscr;
};

/*
* VFP exception registers exposed to user space during signal delivery.
* Fields not relavant to the current VFP architecture are ignored.
*/
struct user_vfp_exc {
unsigned long fpexc;
unsigned long fpinst;
unsigned long fpinst2;
};

#endif /* _ARM_USER_H */
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