From: Tejun Heo Date: Tue, 29 Jun 2010 08:07:11 +0000 (+0200) Subject: workqueue: update cwq alignement X-Git-Tag: v2.6.36-rc1~506^2~43 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0f900049cbe2767d47c2a62b54f0e822e1d66840;p=pandora-kernel.git workqueue: update cwq alignement work->data field is used for two purposes. It points to cwq it's queued on and the lower bits are used for flags. Currently, two bits are reserved which is always safe as 4 byte alignment is guaranteed on every architecture. However, future changes will need more flag bits. On SMP, the percpu allocator is capable of honoring larger alignment (there are other users which depend on it) and larger alignment works just fine. On UP, percpu allocator is a thin wrapper around kzalloc/kfree() and don't honor alignment request. This patch introduces WORK_STRUCT_FLAG_BITS and implements alloc/free_cwqs() which guarantees max(1 << WORK_STRUCT_FLAG_BITS, __alignof__(unsigned long long) alignment both on SMP and UP. On SMP, simply wrapping percpu allocator is enough. On UP, extra space is allocated so that cwq can be aligned and the original pointer can be stored after it which is used in the free path. * Alignment problem on UP is reported by Michal Simek. Signed-off-by: Tejun Heo Cc: Christoph Lameter Cc: Ingo Molnar Cc: Frederic Weisbecker Reported-by: Michal Simek --- Reading git-diff-tree failed