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author | Hirokazu Takata <takata@linux-m32r.org> | 2006-02-20 18:28:17 -0800 |
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committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-02-20 20:00:12 -0800 |
commit | cf535ea52e68e3ee6f4a90cc383faa1ee857f14d (patch) | |
tree | 1217d6b27e99c81b4e9cf003ddd4f71a93ad0c2b /fs | |
parent | b04ec261bd64f927bf3fce5cf9eeb0225557939d (diff) |
[PATCH] m32r: update sys_tas() routine
This patch updates and fixes sys_tas() routine for m32r.
In the previous implementation, a lockup rarely caused at sys_tas()
routine in SMP environment.
> > The problem is that touching *addr will generate an oops if that page isn't
> > paged in. If we convert it to use get_user() then that's an improvement,
> > but we must not run get_user() under spinlock or local_irq_disable().
I rewrote sys_tas() routine by using "lock -> unlock" instructions, and
utilizing the m32r's interrupt handling characteristics; the m32r processor
can accept interrupts only at the 32-bit instruction boundary. So, the
"unlock" instruction can be executed continuously after the "lock"
instruction execution without any interruptions.
In addition, to solve such a page_fault problem, I use a fixup code like
get_user().
And, as for the kernel lockup problem, we found that a calling
do_page_fault() routine with disabling interrupts might cause a lockup at
flush_tlb_others(), because we checked a completion of IPI handler's
operations in a spin-locked critical section.
Therefore, by using "lock -> unlock" code, we can implement the sys_tas()
rouitine without disabling interrupts explicitly, then no lockups would
happen at flush_tlb_others(), I hope.
Compile check and some working test in SMP environment have done.
Signed-off-by: Hirokazu Takata <takata@linux-m32r.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'fs')
0 files changed, 0 insertions, 0 deletions