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author | Linus Torvalds <torvalds@linux-foundation.org> | 2012-02-19 19:46:36 (GMT) |
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committer | Ingo Molnar <mingo@elte.hu> | 2012-02-20 08:30:18 (GMT) |
commit | 986cb48c5a4de0085db94d343b4e7dcf54355ec1 (patch) | |
tree | a25140de28f6b73dca92600273f589719af090b3 /kernel/irq | |
parent | b01543dfe67bb1d191998e90d20534dc354de059 (diff) | |
download | linux-986cb48c5a4de0085db94d343b4e7dcf54355ec1.tar.xz |
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 <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1202191139260.10000@i5.linux-foundation.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/irq')
0 files changed, 0 insertions, 0 deletions