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devres: Align data[] to ARCH_KMALLOC_MINALIGN

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Initially we bumped into problem with 32-bit aligned atomic64_t
on ARC, see [1]. And then during quite lengthly discussion Peter Z.
mentioned ARCH_KMALLOC_MINALIGN which IMHO makes perfect sense.
If allocation is done by plain kmalloc() obtained buffer will be
ARCH_KMALLOC_MINALIGN aligned and then why buffer obtained via
devm_kmalloc() should have any other alignment?

This way we at least get the same behavior for both types of
allocation.

[1] http://lists.infradead.org/pipermail/linux-snps-arc/2018-July/004009.html
[2] http://lists.infradead.org/pipermail/linux-snps-arc/2018-July/004036.html

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Greg KH <greg@kroah.com>
Cc: <stable@vger.kernel.org> # 4.8+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alexey Brodkin 2018-10-31 18:25:47 +03:00 committed by Greg Kroah-Hartman
parent 651022382c
commit a66d972465
1 changed files with 8 additions and 2 deletions
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10
drivers/base/devres.c
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@ -26,8 +26,14 @@ struct devres_node {
struct devres {
struct devres_node node;
/* -- 3 pointers */
unsigned long long data[]; /* guarantee ull alignment */
/*
* Some archs want to perform DMA into kmalloc caches
* and need a guaranteed alignment larger than
* the alignment of a 64-bit integer.
* Thus we use ARCH_KMALLOC_MINALIGN here and get exactly the same
* buffer alignment as if it was allocated by plain kmalloc().
*/
u8 __aligned(ARCH_KMALLOC_MINALIGN) data[];
};
struct devres_group {