On Tue, 19 Feb 2013, Ian Campbell wrote:
> On ARM we want these to be the same size on 32- and 64-bit.
>
> This is an ABI change on ARM. X86 does not change.
>
> Signed-off-by: Ian Campbell <ian.campb...@citrix.com>
> Cc: Jan Beulich <jbeul...@suse.com>
> Cc: Keir (Xen.org) <k...@xen.org>
> Cc: Tim Deegan <t...@xen.org>
> Cc: Stefano Stabellini <stefano.stabell...@eu.citrix.com>
> Cc: linux-arm-ker...@lists.infradead.org
> Cc: xen-de...@lists.xen.org
> Cc: Konrad Rzeszutek Wilk <konrad.w...@oracle.com>
> ---
> Changes since V3
> s/read_evtchn_pending_sel/xchg_xen_ulong/ in a comment.
> Changes since V2
> Add comments about the correct bitops to use, and on the ordering/barrier
> requirements on xchg_xen_ulong.
> Changes since V1
> use find_first_set not __ffs
> fix some more unsigned long -> xen_ulong_t
> use more generic xchg_xen_ulong instead of ...read_evtchn...
still doesn't apply to 3.8
> do {
> - unsigned long pending_words;
> + xen_ulong_t pending_words;
>
> vcpu_info->evtchn_upcall_pending = 0;
>
> if (__this_cpu_inc_return(xed_nesting_count) - 1)
> goto out;
>
> -#ifndef CONFIG_X86 /* No need for a barrier -- XCHG is a barrier on x86. */
> - /* Clear master flag /before/ clearing selector flag. */
> - wmb();
> -#endif
> - pending_words = xchg(&vcpu_info->evtchn_pending_sel, 0);
> + /*
> + * Master flag must be /before/ clearing selector
> + * flag. xchg_xen_ulong must contain an appropriate
> + * barrier.
> + */
Master flag must be *cleared* ...
> + pending_words =
> xchg_xen_ulong(&vcpu_info->evtchn_pending_sel, 0);
>
> start_word_idx = __this_cpu_read(current_word_idx);
> start_bit_idx = __this_cpu_read(current_bit_idx);
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