Hi Alexey,
On Mon, Jul 9, 2018 at 9:22 AM Alexey Brodkin Alexey.Brodkin@synopsys.com wrote:
On Mon, 2018-07-09 at 09:07 +0200, Geert Uytterhoeven wrote:
On Mon, Jul 9, 2018 at 7:49 AM Greg KH greg@kroah.com wrote:
On Mon, Jul 09, 2018 at 07:44:44AM +0300, Alexey Brodkin wrote:
Depending on ABI "long long" type of a particular 32-bit CPU might be aligned by either word (32-bits) or double word (64-bits).
Or even 16-bit (on e.g. m68k).
Indeed, thanks for the note! Will add this in my v3.
Note that in this particular case, the field will probably always be aligned to 4 bytes, as the struct will be allocated using *alloc().
For ARC I'd like this fix to be back-ported starting from v4.8 where we added support of "native" atomic64_t, see commit ce6365270ecd (" ARCv2: Implement atomic64 based on LLOCKD/SCONDD instructions").
What about m68k, do you have any preference of earliest kernel version where this fix might be useful?
Given m68k is 32-bit, it will access atomic64_t variables while holding a spinlock, so it should still be safe without this change.
Not to mention no one will try etnaviv on m68k ;-)
Gr{oetje,eeting}s,
Geert