Yinghai Lu [Mon, 14 Apr 2008 01:42:31 +0000 (18:42 -0700)]
x86: checking aperture size order
some systems are using 32M for gart and agp when memory is less than 4G.
Kernel will reject and try to allcate another 64M that is not needed,
and we will waste 64M of perfectly good RAM.
this patch adds a workaround by checking aper_base/order between NB and
agp bridge. If they are the same, and memory size is less than 4G, it
will allow it.
Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Yinghai Lu [Sun, 13 Apr 2008 08:11:41 +0000 (01:11 -0700)]
x86: agp_gart size checking for buggy device
while looking at Rafael J. Wysocki's system boot log,
I found a funny printout:
Node 0: aperture @ de000000 size 32 MB
Aperture too small (32 MB)
AGP bridge at 00:04:00
Aperture from AGP @ de000000 size 4096 MB (APSIZE 0)
Aperture too small (0 MB)
Your BIOS doesn't leave a aperture memory hole
Please enable the IOMMU option in the BIOS setup
This costs you 64 MB of RAM
Mapping aperture over 65536 KB of RAM @ 4000000
...
agpgart: Detected AGP bridge 20
agpgart: Aperture pointing to RAM
agpgart: Aperture from AGP @ de000000 size 4096 MB
agpgart: Aperture too small (0 MB)
agpgart: No usable aperture found.
agpgart: Consider rebooting with iommu=memaper=2 to get a good aperture.
it means BIOS allocated the correct gart on the NB and AGP bridge, but
because a bug in the silicon (the agp bridge reports the wrong order,
it wants 4G instead) the kernel will reject that allocation.
Also, because the size is only 32MB, and we try to get another 64M for gart,
late fix_northbridge can not revert that change because it still reads
the wrong size from agp bridge.
So try to double check the order value from the agp bridge, before calling
aperture_valid().
[ mingo@elte.hu: 32-bit fix. ]
Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Thomas Gleixner [Mon, 5 May 2008 16:13:50 +0000 (18:13 +0200)]
x86: irq_32 move 4kstacks code to one place
Move the 4KSTACKS related code to one place. This allows to un#ifdef
do_IRQ() and share the executed on stack for the stack overflow printk
and the softirq call.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Andi Kleen [Mon, 5 May 2008 10:36:38 +0000 (12:36 +0200)]
i386: Execute stack overflow warning on interrupt stack v2
Previously the reporting printk would run on the process stack, which risks
overflow an already low stack. Instead execute it on the interrupt stack.
This makes it more likely for the printk to make it actually out.
It adds one not taken test/branch more to the interrupt path when
stack overflow checking is enabled. We could avoid that by duplicating
more code, but that seemed not worth it.
Alan Mayer [Tue, 15 Apr 2008 20:36:56 +0000 (15:36 -0500)]
x86: change FIRST_SYSTEM_VECTOR to a variable
The SGI UV system needs several more system vectors than a vanilla
x86_64 system. Rather than burden the other archs with extra system
vectors that they don't use, change FIRST_SYSTEM_VECTOR to a variable,
so that it can be dynamic.
Signed-off-by: Alan Mayer <ajm@sgi.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Alan Mayer [Wed, 26 Mar 2008 21:11:31 +0000 (16:11 -0500)]
x86: resize NR_IRQS for large machines
On machines with very large numbers of cpus, tables that are dimensioned
by NR_IRQS get very large, especially the irq_desc table. They are also
very sparsely used. When the cpu count is > MAX_IO_APICS, use MAX_IO_APICS
to set NR_IRQS, otherwise use NR_CPUS.
Signed-off-by: Alan Mayer <ajm@sgi.com> Reviewed-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Venki Pallipadi [Mon, 12 May 2008 13:43:34 +0000 (15:43 +0200)]
x86: remove 6 bank limitation in 64 bit MCE reporting code
Eliminate the 6 bank restriction in 64 bit mce reporting code. This
restriction is artificial (due to static creation of sysfs files) and 32
bit code does not have any such restriction.
This change helps in reporting the details of machine checks on a
machine check exception with errors in bank 6 and above on CPUs that
support those banks. Without the patch, machine check errors in those
banks are not reported.
We still have 128 (MCE_EXTENDED_BANK) bank restriction instead of max
256 supported in hardware. That is not changed in the patch below as it
will have some user level mcelog utility dependency, with bank 128 being
used for thermal reporting currently.
The patch below does not create sysfs control (bankNctl) for banks
higher than 6 as well. That needs some pre-cleanup in /sysfs mce layout,
removal of per cpu /sysfs entries for bankctl as they are really global
system level control today. That change will follow. This basic change
is critical to report the detailed errors on banks higher than 6.
Thomas Gleixner [Sat, 10 May 2008 19:42:14 +0000 (21:42 +0200)]
x86: print info about available HPET quirk
We have a lot of HPET quirks available which might force enable HPET
even when the BIOS does not enable it. Some of those quirks depend on
the command line option "hpet=force".
Andrew pointed out that hoping that the user will find out about this
boot option is not really helpful.
Emit a kernel info which informs the user about the "hpet=force" boot
option when we enter a quirk which depends on this option and the user
did not provide it.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Add quirk to allow forced usage of HPET on ATI SB400.
I stumbled over machines where HPET is enabled but not reported
by BIOS. This patch configures the HPET base address and makes
it known to the OS.
Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Carlos R. Mafra [Mon, 5 May 2008 23:11:22 +0000 (20:11 -0300)]
x86: clean up computation of HPET .mult variables
While reading through the HPET code I realized that the
computation of .mult variables could be done with less
lines of code, resulting in a 1.6% text size saving
for hpet.o
So I propose the following patch, which applies against
today's Linus -git tree.
can also be streamlined with the observation that hpet_period and hpet_freq are
inverse to each other (in proper units).
So instead of computing hpet_freq and using (schematically)
div_sc(hpet_freq, 10^9, shift) we use the trick of calling with the
arguments in reverse order, div_sc(10^6, hpet_period, shift).
The different power of ten is due to frequency being in Hertz (1/sec)
and the period being in units of femtosecond. Explicitly,
mult = (hpet_freq * 2^shift)/10^9 (before)
mult = (10^6 * 2^shift)/hpet_period (after)
because hpet_freq = 10^15/hpet_period.
The comments in the code are also updated to reflect the changes.
As a result,
text data bss dec hex filename
2957 425 92 3474 d92 arch/x86/kernel/hpet.o
3006 425 92 3523 dc3 arch/x86/kernel/hpet.o.old
a 1.6% reduction in text size.
Signed-off-by: Carlos R. Mafra <crmafra@ift.unesp.br> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Markus Metzger [Tue, 8 Apr 2008 09:01:58 +0000 (11:01 +0200)]
x86, ptrace: PEBS support
Polish the ds.h interface and add support for PEBS.
Ds.c is meant to be the resource allocator for per-thread and per-cpu
BTS and PEBS recording.
It is used by ptrace/utrace to provide execution tracing of debugged tasks.
It will be used by profilers (e.g. perfmon2).
It may be used by kernel debuggers to provide a kernel execution trace.
Changes in detail:
- guard DS and ptrace by CONFIG macros
- separate DS and BTS more clearly
- simplify field accesses
- add functions to manage PEBS buffers
- add simple protection/allocation mechanism
- added support for Atom
Opens:
- buffer overflow handling
Currently, only circular buffers are supported. This is all we need
for debugging. Profilers would want an overflow notification.
This is planned to be added when perfmon2 is made to use the ds.h
interface.
- utrace intermediate layer
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
James Bottomley [Sat, 10 May 2008 14:01:48 +0000 (09:01 -0500)]
x86: [VOYAGER] fix duplicate phys_cpu_present_map symbol
The phys_cpu_present_map is an expected symbol in the SMP harness.
Unfortunately, x86 recently moved this and a few others to
kernel/setup.c where it doesn't quite work because voyager has to
define its own. Use CONFIG_X86_LOCAL_APIC to isolate these
definitions and fix up another area in setup.c where CONFIG_X86_SMP
should be used instead of CONFIG_SMP.
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com> Cc: WANG Cong <xiyou.wangcong@gmail.com> Cc: toralf.foerster@gmx.de Cc: Mike Travis <travis@sgi.com> Cc: Alexey Starikovskiy <astarikovskiy@suse.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Takashi Iwai [Mon, 12 May 2008 13:43:30 +0000 (15:43 +0200)]
x86/pci: fix broken ISA DMA
Rene Herman reported:
> commit 8779f2fc3b84ebb6c5181fb13d702e9944c16069
>
> "x86: don't try to allocate from DMA zone at first"
>
> breaks all of ISA DMA. Or all of ALSA ISA DMA at least. All
> ISA soundcards are silent following that commit -- no error
> messages, everything appears fine, just silence.
That patch is buggy. We had an implicit assumption that
dev = NULL for ISA devices that require 24bit DMA.
The recent work on x86 dma_alloc_coherent() breaks the ISA DMA buffer
allocation, which is represented by "dev = NULL" and requires 24bit
DMA implicitly.
Bisected-by: Rene Herman <rene.herman@keyaccess.nl> Signed-off-by: Takashi Iwai <tiwai@suse.de> Tested-by: Rene Herman <rene.herman@keyaccess.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Linus Torvalds [Mon, 12 May 2008 17:14:22 +0000 (10:14 -0700)]
Fix up 'need_resched()' definition
We should not go through the task pointer to get at the thread info,
since it's usually cheaper to just access the thread info directly.
So don't make the code look up 'current', when we can just use the
thread info accessor functions directly. This generally avoids one
level of indirection and tends to work better together with code that
also looks at other thread flags (eg preempt_count).
Russell King [Sun, 20 Apr 2008 12:57:26 +0000 (13:57 +0100)]
[ARM] dyntick: Remove obsolete and unused ARM dyntick support
dyntick is superseded by the clocksource/clockevent infrastructure,
using the NO_HZ configuration option. No one implements dyntick on
ARM anymore, so it's pointless keeping it around. Remove dyntick
support.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Stick with the original pattern, but make sure the 32-bit code
actually comes first!
Reported by Al Viro.
Signed-off-by: H. Peter Anvin <hpa@zytor.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Al Viro <viro@zeniv.linux.org.uk>
...
CC arch/mips/emma2rh/markeins/setup.o
/home/bunk/linux/kernel-2.6/git/linux-2.6/arch/mips/emma2rh/markeins/setup.c:79: error: conflicting types for 'clock'
/home/bunk/linux/kernel-2.6/git/linux-2.6/include/linux/clocksource.h:96: error: previous declaration of 'clock' was here
make[2]: *** [arch/mips/emma2rh/markeins/setup.o] Error 1
<-- snip -->
[Ralf: reformated to 80 colums after the fix and marked emma2rh_clock as
__initdata]
Signed-off-by: Adrian Bunk <bunk@kernel.org> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Only MIPS32 and MIPS64 CPUs implement clz/dclz. Therefore don't export
__ilog2() for non MIPS32/MIPS64 cpus and use generic __fls bitop code for
these cpus.
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Sergei Shtylyov [Wed, 30 Apr 2008 19:29:04 +0000 (23:29 +0400)]
[MIPS] Pb1200/DBAu1200 code style cleanup
Fix several errors and warnings given by checkpatch.pl:
- use of C99 // comments;
- initialization of a 'static' variable to 0;
- space after opening and before closing parentheses;
- missing space between 'for' and opening parenthesis;
- macros with complex values not enclosed in parentheses;
- printk() without KERN_* facility level;
- unnecessary braces for single-statement block;
- using simple_strtol() where strict_strtol() could be used;
- line over 80 characters.
In addition to these changes, also do the following:
- mention DBAu1200 board in the Makefile;
- replace the group of #include/#ifdef directives by a single
#include <au1xxx.h> since this header contains the needed stuff;
- properly indent the blocks;
- insert spaces between operator and its operands, remove excess spaces
there;
- remove needless parentheses and add some for clarity;
- replace numeric literals/expressions with the matching macros;
- remove space after the type cast's closing parenthesis;
- reduce pb1200_setup_cascade() to the single 'return' statement;
- reduce the number of printed empty lines in the so-called CPLD
workaround;
- remove #undef AU1X00_EXTERNAL_INT since that macro is not defined
anywhere;
- replace spaces after the macro name with tabs in the #define directives;
- remove excess tabs after the macro name in the #define directives;
- fix typo in the BCSR_RESETS_PWMR1mUX macro's name;
- group all Pb1200 PCMCIA definitions together;
- put the function's result type and name/parameters on the same line;
- insert missing and remove excess new lines;
- make the multi-line comment style consistent with the kernel style
elsewhere by adding empty first line and/or adding space/asterisk on
their left side;
- fix typos/errors, capitalize acronyms, etc. in the comments;
- combine some comments;
- update MontaVista copyright;
- remove Pete Popov's old email address...
Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Sergei Shtylyov [Wed, 30 Apr 2008 19:18:35 +0000 (23:18 +0400)]
[MIPS] Alchemy common headers style cleanup
Fix several errors and warnings given by checkpatch.pl:
- space after opening and before closing parentheses;
- opening brace following 'struct' not on the same line;
- leading spaces instead of tabs;
- use of C99 // comments;
- macros with complex values not enclosed in parentheses;
- missing space between the type and asterisk in a variable declaration;
- space between asterisk and function name;
- including <asm/io.h> instead of <linux/io.h> and <asm/irq.h> instead of
<linux/irq.h>;
- use of '__inline__' instead of 'inline';
- space between function name and opening parenthesis;
- line over 80 characters.
In addition to these changes, also do the following:
- remove needless parentheses;
- insert spaces between operator and its operands;
- replace spaces after the macro name with tabs in the #define directives and
after the type in the structure field declarations;
- remove excess tabs after the macro name in the #define directives and in the
'extern' variable declarations;
- remove excess spaces between # and define for the SSI_*_MASK macros to align
with other such macros;
- put '||' operator on the same line with its first operand;
- properly indent multi-line function prototypes;
- make the multi-line comment style consistent with the kernel style elsewhere
by adding empty first line and/or adding space/asterisk on their left side;
- make two-line comments that only have one line of text one-line;
- convert the large multi-line comment in au1xxx_ide.h into several one-liners,
replace spaces with tabs there;
- fix typos/errors, capitalize acronyms, etc. in the comments;
- insert missing and remove excess new lines;
- update MontaVista copyright;
- remove Pete Popov's and Steve Longerbeam's old email addresses...
Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Jeff Garzik [Fri, 18 Apr 2008 23:23:01 +0000 (19:23 -0400)]
[MIPS] msp_hwbutton.c: minor irq handler cleanups
- remove always-true test
- neaten request_irq() indentation
This change's main purpose is to prepare for the patchset in
jgarzik/misc-2.6.git#irq-remove, that explores removal of the
never-used 'irq' argument in each interrupt handler.
Signed-off-by: Jeff Garzik <jgarzik@redhat.com> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
do_brk's return value was stored in an unsigned long variable before being
tested for less than zero making the test always fail. Also do_brk's
called irix_map_prda_page wasn't forwarding do_brk() success.
Bug checking the return value of do_brk() and initial fix for it found
by Roel Kluin <12o3l@tiscali.nl>.
Sergei Shtylyov [Sat, 5 Apr 2008 18:16:21 +0000 (22:16 +0400)]
[MIPS] Alchemy: SMBus resource fix
The Alchemy platform code registers the SMBus device using the virtual
address of its registers instead of the physical one -- fix this, taking
into account that actually the whole megabyte is decoded by any of the
programmable serial controllers (one of which is SMBus), and that all the
Alchemy peripherals are directly mappable into KSEG1 kernel space and
therefore ioremap() call would just boil down to CKSEG1ADDR() invocation.
Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This patch fixes bug #10627 which caused the compilation error below.
CC [M] drivers/usb/c67x00/c67x00-ll-hpi.o
drivers/usb/c67x00/c67x00-ll-hpi.c: In function `ll_recv_msg':
drivers/usb/c67x00/c67x00-ll-hpi.c:243: erreur: `HZ' undeclared (first use in this function)
drivers/usb/c67x00/c67x00-ll-hpi.c:243: erreur: (Each undeclared identifier is reported only once
drivers/usb/c67x00/c67x00-ll-hpi.c:243: erreur: for each function it appears in.)
Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Linus Torvalds [Mon, 12 May 2008 14:29:08 +0000 (07:29 -0700)]
Merge branch 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc
* 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc:
[POWERPC] ppc: More compile fixes
[POWERPC] ppc: Don't run prom_init_check for arch/ppc builds
[POWERPC] ppc: Include <asm/cacheflush.h> in kernel/ppc_ksyms.c
[POWERPC] ppc: Use ebony_defconfig for defconfig
[POWERPC] Fix default cputable entries for e200 and e500 families
Alan Cox [Mon, 12 May 2008 11:29:25 +0000 (12:29 +0100)]
strip: Fix termios assumption
Strip assumes that the tty drivers always have a set_termios method which
may not be true. Check this when binding to the tty so that we don't oops
later.
Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Paul Mackerras [Mon, 12 May 2008 12:57:51 +0000 (22:57 +1000)]
[POWERPC] ppc: More compile fixes
This fixes a few more miscellaneous compile problems with ARCH=ppc.
1. Don't compile devres.c on ARCH=ppc, it doesn't have ioremap_flags.
2. Include <asm/irq.h> in setup.c for the __DO_IRQ_CANON definition.
3. Include <linux/proc_fs.h> in residual.c for the
definition of create_proc_read_entry.
4. Fix xchg_ptr to be a static inline to eliminate a compiler warning.
David S. Miller [Mon, 12 May 2008 10:29:11 +0000 (03:29 -0700)]
syncppp: Fix crashes.
The syncppp layer wants a mid-level netdev private pointer.
It was using netdev->priv but that only worked by accident,
and thus this scheme was broken when the device private
allocation strategy changed.
Add a proper mid-layer private pointer for uses like this,
update syncppp and all users, and remove the HDLC_PPP broken
tag from drivers/net/wan/Kconfig
Signed-off-by: David S. Miller <davem@davemloft.net>
Wei Yongjun [Fri, 9 May 2008 22:11:53 +0000 (15:11 -0700)]
sctp: Add address type check while process paramaters of ASCONF chunk
If socket is create by AF_INET type, add IPv6 address to asoc will cause
kernel panic while packet is transmitted on that transport.
This patch add address type check before process paramaters of ASCONF
chunk. If peer is not support this address type, return with error
invald parameter.
Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com> Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Wei Yongjun [Fri, 9 May 2008 22:11:17 +0000 (15:11 -0700)]
sctp: Do not enable peer IPv6 address support on PF_INET socket
If socket is create by PF_INET type, it can not used IPv6 address to
send/recv DATA, So we can not used IPv6 address even if peer tell us it
support IPv6 address.
This patch fix to only enabled peer IPv6 address support on PF_INET6 socket.
Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com> Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Matheos Worku [Mon, 12 May 2008 10:10:59 +0000 (03:10 -0700)]
niu: Determine the # of ports from the card's VPD data
Determine the number of physical ports from the card's VPD data.
Previous fix failed on Maramba platform which doesn't have the
"board-model" property. This fix uses the "model" property which
exists on all cards and Neptune based motherboards.
cstyle cleanup included.
Signed-off-by: Matheos Worku <matheos.worku@sun.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Andrew Price [Thu, 1 May 2008 10:55:38 +0000 (11:55 +0100)]
[GFS2] Fix cast from unsigned int to s64
This fixes bz 444829 where allocating a new block caused gfs2 file systems to
report 0 bytes used in df. It was caused by a broken cast from an unsigned int
in gfs2_block_alloc() to a negative s64 in gfs2_statfs_change(). This patch
casts the unsigned int to an s64 before the unary minus is applied.
Signed-off-by: Andrew Price <andy@andrewprice.me.uk> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Bob Peterson [Tue, 29 Apr 2008 17:35:48 +0000 (12:35 -0500)]
[GFS2] filesystem consistency error from do_strip
This patch fixes a GFS2 filesystem consistency error reported from
function do_strip. The problem was caused by a timing window
that allowed two vfs inodes to be created in memory that point
to the same file. The problem is fixed by making the vfs's
iget_test, iget_set mechanism check and set a new bit in the
in-core gfs2_inode structure while the vfs inode spin_lock is held.
Signed-off-by: Bob Peterson <rpeterso@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Paul Mackerras [Mon, 12 May 2008 04:20:35 +0000 (14:20 +1000)]
[POWERPC] Fix default cputable entries for e200 and e500 families
Commit 76bc080ef5a34aedb63e1691f28c6b42f3468e4e ("POWERPC] Make default
cputable entries reflect selected CPU family") added default entries
for the e200 and e500 families, but missed a closing brace on those
entries, as pointed out by David Gibson. This adds the closing braces.
Al Viro [Mon, 12 May 2008 03:55:10 +0000 (11:55 +0800)]
[Blackfin] arch: Blackfin checksum annotations
FSVOtest in this case, since I don't have the hardware...
However, all changes seen by gcc are actually
- explicit cast to unsigned short in return expression of functions
returning unsigned short
- csum_fold() return type changed from unsigned int to __sum16
(unsigned short), same as for all other architecture and as net/* expects;
expression actually returned is ((~(sum << 16)) >> 16) with sum being
unsigned 32bit, so it's (a) going to fit into the range of unsigned short
and (b) had been unsigned all along, so no sign expansion mess happened.
Tested-by: Bryan Wu <cooloney@kernel.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: David Miller <davem@davemloft.net> Signed-off-by: Bryan Wu <cooloney@kernel.org>