From: Linus Torvalds Date: Sun, 19 Feb 2012 19:46:36 +0000 (-0800) Subject: x86-32/irq: Don't switch to irq stack for a user-mode irq X-Git-Tag: v3.4-rc1~193^2~9 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=986cb48c5a4de0085db94d343b4e7dcf54355ec1;p=pandora-kernel.git x86-32/irq: Don't switch to irq stack for a user-mode irq If the irq happens in user mode, our kernel stack is empty (apart from the pt_regs themselves, of course), so there's no need or advantage to switch. And it really doesn't save any stack space, quite the reverse: it means that a nested interrupt cannot switch irq stacks. So instead of saving kernel stack space, it actually causes the potential for *more* stack usage. Also simplify the preemption count copy when we do switch stacks: just copy the whole preemption count, rather than just the softirq parts of it. There is no advantage to the partial copy: it is more effort to get a less correct result. Signed-off-by: Linus Torvalds Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1202191139260.10000@i5.linux-foundation.org Signed-off-by: Ingo Molnar --- Reading git-diff-tree failed