devres: Align data[] to ARCH_KMALLOC_MINALIGN

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 <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: David Laight <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Vineet Gupta <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Greg KH <[email protected]>
Cc: <[email protected]> # 4.8+
Signed-off-by: Greg Kroah-Hartman <[email protected]>
This commit is contained in:
Alexey Brodkin 2018-10-31 18:25:47 +03:00 • committed by Greg Kroah-Hartman
commit a66d972465

View file

@ -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 {