Luis R. Rodriguez | 3 Jul 20:17 2015

RFC: default ioremap_*() variant defintions

The 0-day build bot detected a build issue on a patch not upstream yet that
makes a driver use iorempa_uc(), this call is now upstream but we have no
drivers yet using it, the patch in question makes the atyfb framebuffer driver
use it. The build issue was the lack of the ioremap_uc() call being implemented
on some non-x86 architectures. I *thought* I had added boiler plate code to map
the ioremap_uc() call to ioremap_nocache() for archs that do not already define
their own iorempa_uc() call, but upon further investigation it seems that was
not the case but found that this may be a bit different issue altogether.

The way include/asm-generic/io.h works for ioremap() calls and its variants is:

#ifndef CONFIG_MMU                                                              
#ifndef ioremap                                                                 
#define ioremap ioremap                                                         
static inline void __iomem *ioremap(phys_addr_t offset, size_t size)            
        return (void __iomem *)(unsigned long)offset;                           
#define iounmap iounmap                                                         

static inline void iounmap(void __iomem *addr)                                  
#endif /* CONFIG_MMU */  

That's the gist of it, but the catch here is the ioremap_*() variants and where
(Continue reading)

Laurent Dufour | 29 Jun 16:25 2015

[PATCH] mm: cleaning per architecture MM hook header files

The commit 2ae416b142b6 ("mm: new mm hook framework") introduced an empty
header file (mm-arch-hooks.h) for every architecture, even those which
doesn't need to define mm hooks.

As suggested by Geert Uytterhoeven, this could be cleaned through the use
of a generic header file included via each per architecture
asm/include/Kbuild file.

The powerpc architecture is not impacted here since this architecture has
to defined the arch_remap MM hook.

Signed-off-by: Laurent Dufour <ldufour <at>>
Suggested-by: Geert Uytterhoeven <geert <at>>
CC: Andrew Morton <akpm <at>>
CC: linux-arch <at>
CC: linux-mm <at>
CC: linux-kernel <at>
 arch/alpha/include/asm/Kbuild               |  1 +
 arch/alpha/include/asm/mm-arch-hooks.h      | 15 ---------------
 arch/arc/include/asm/Kbuild                 |  1 +
 arch/arc/include/asm/mm-arch-hooks.h        | 15 ---------------
 arch/arm/include/asm/Kbuild                 |  1 +
 arch/arm/include/asm/mm-arch-hooks.h        | 15 ---------------
 arch/arm64/include/asm/Kbuild               |  1 +
 arch/arm64/include/asm/mm-arch-hooks.h      | 15 ---------------
 arch/avr32/include/asm/Kbuild               |  1 +
 arch/avr32/include/asm/mm-arch-hooks.h      | 15 ---------------
 arch/blackfin/include/asm/Kbuild            |  1 +
 arch/blackfin/include/asm/mm-arch-hooks.h   | 15 ---------------
(Continue reading)

Geert Uytterhoeven | 28 Jun 11:24 2015

atomic64 on 32-bit vs 64-bit (was: Re: Add virtio gpu driver.)

On Fri, Jun 26, 2015 at 10:52 PM, Linux Kernel Mailing List
<linux-kernel <at>> wrote:
> Gitweb:;a=commit;h=dc5698e80cf724770283e10414054662bdf6ccfa
> Commit:     dc5698e80cf724770283e10414054662bdf6ccfa
> Parent:     16e3247da7f71f8c31f4330f739f6192a00c8b51
> Refname:    refs/heads/master
> Author:     Dave Airlie <airlied <at>>
> AuthorDate: Mon Sep 9 10:02:56 2013 +1000
> Committer:  Gerd Hoffmann <kraxel <at>>
> CommitDate: Wed Jun 3 14:17:38 2015 +0200
>     Add virtio gpu driver.
>     This patch adds a kms driver for the virtio gpu.  The xorg modesetting
>     driver can handle the device just fine, the framebuffer for fbcon is
>     there too.
>     Qemu patches for the host side are under review currently.
>     The pci version of the device comes in two variants: with and without
>     vga compatibility.  The former has a extra memory bar for the vga
>     framebuffer, the later is a pure virtio device.  The only concern for
>     this driver is that in the virtio-vga case we have to kick out the
>     firmware framebuffer.
>     Initial revision has only 2d support, 3d (virgl) support requires
>     some more work on the qemu side and will be added later.
>     Signed-off-by: Dave Airlie <airlied <at>>
>     Signed-off-by: Gerd Hoffmann <kraxel <at>>
(Continue reading)

'LEUNG CHEUNG' | 21 Jun 19:05 2015


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Waiman Long | 19 Jun 17:49 2015

[PATCH v5 0/3] locking/qrwlock: More optimizations in qrwlock

 - Add a new patch to rename function names to sync up to qspinlock
   naming convention.
 - Move the extended qrwlock structure to the header file as requested
   by Will Deacon so that it can also be used in the ARM's architecture
   specific code.

 - Remove the unnecessary _QW_WMASK check in

 - Fix incorrect commit log message in patch 1.

 - Add microbenchmark data for the second patch

This patch set contains 2 patches on qrwlock. The first one is to
optimize the interrupt context reader slowpath.  The second one is
to optimize the writer slowpath.

*** BLURB HERE ***

Waiman Long (3):
  locking/qrwlock: Rename functions to queued_*()
  locking/qrwlock: Better optimization for interrupt context readers
  locking/qrwlock: Don't contend with readers when setting _QW_WAITING

 arch/x86/include/asm/qrwlock.h      |    7 ++--
 include/asm-generic/qrwlock.h       |   58 +++++++++++++++++-----------------
(Continue reading)

Vineet Gupta | 18 Jun 08:47 2015

subtle side effect of commit a1c48bb160f836

Hi Geert,

commit a1c48bb160f8368 "Makefile: Fix unrecognized cross-compiler command line
options" moved ARCH specific cc option handling before common -Os/O2 setup.

For ARC this had a subtle effect that we can no longer over-ride generic -O2 with
-O3, hence a performance regression observed going from 3.13 to 3.18 (the above
commit went into 3.16)

I want to understand how to properly fix this. Moving the include of arch makefile
will bring back the old issue. I can introduce another option to set default optim
level, but only arc/m32r care about it anyways.

Maria-Elisabeth Schaeffler | 16 Jun 13:19 2015


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Sylvain Chouleur | 15 Jun 15:01 2015

[PATCH] rtc-cmos: Support of century field

If century field is supported by the RTC CMOS device, then we should use
it and do not consider years greater that 169 as an error.

For information, the year field of the rtc_time structure contains the
value to add to 1970 to obtain the current year.
This was a hack to be able to support years from 1970 to 2069.
This patch remains compatible with this implementation.

Signed-off-by: Sylvain Chouleur <sylvain.chouleur <at>>
 include/asm-generic/rtc.h | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/include/asm-generic/rtc.h b/include/asm-generic/rtc.h
index fa86f240c874..4e3b6558331e 100644
--- a/include/asm-generic/rtc.h
+++ b/include/asm-generic/rtc.h
 <at>  <at>  -16,6 +16,9  <at>  <at> 
 #include <linux/rtc.h>
 #include <linux/bcd.h>
 #include <linux/delay.h>
+#include <linux/acpi.h>

 #define RTC_PIE 0x40		/* periodic interrupt enable */
 #define RTC_AIE 0x20		/* alarm interrupt enable */
 <at>  <at>  -46,6 +49,7  <at>  <at>  static inline unsigned int __get_rtc_time(struct rtc_time *time)
 	unsigned char ctrl;
(Continue reading)

Baolin Wang | 12 Jun 09:19 2015

[PATCH v5 00/24] Convert the posix_clock_operations and k_clock structure to ready for 2038

This patch series changes the 32-bit time types (timespec/itimerspec) to
the 64-bit types (timespec64/itimerspec64), since 32-bit time types will
break in the year 2038 on 32bit systems.

This patch series introduces new methods with timespec64/itimerspec64 type,
and removes the old ones with timespec/itimerspec type for posix_clock_operations
and k_clock structure.

Changes since v4:
- Rebase the patch series.
- Modify the subject line and the changelog.

Changes since v3:
- Fix some introducing bugs.

Changes since v2:
- Split the syscall conversion patch into small some patches.

Changes since V1:
- Split some patch into small patch.
- Add some default function for new 64bit methods for syscall function.
- Move do_sys_settimeofday() function to head file.
- Modify the EXPORT_SYMPOL issue.
- Add new 64bit methods in cputime_nsecs.h file.

Baolin Wang (24):
  time: Introduce struct itimerspec64
  timekeeping: Introduce current_kernel_time64()
(Continue reading)

aswamina | 9 Jun 17:17 2015

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Waiman Long | 9 Jun 17:19 2015

[PATCH 0/2 v2] locking/qrwlock: Fix interrupt handling problem

 - Add microbenchmark data for the second patch

This patch series contains 2 patches on qrwlock. The first one is just
a recap of the patch that I sent a few weeks ago. The second one is to
optimize the writer slowpath.

Waiman Long (2):
  locking/qrwlock: Fix bug in interrupt handling code
  locking/qrwlock: Don't contend with readers when setting _QW_WAITING

 include/asm-generic/qrwlock.h |    4 +-
 kernel/locking/qrwlock.c      |   42 +++++++++++++++++++++++++++++++---------
 2 files changed, 34 insertions(+), 12 deletions(-)