forked from luck/tmp_suning_uos_patched
cf535ea52e
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> |
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| alpha | ||
| arm | ||
| arm26 | ||
| cris | ||
| frv | ||
| h8300 | ||
| i386 | ||
| ia64 | ||
| m32r | ||
| m68k | ||
| m68knommu | ||
| mips | ||
| parisc | ||
| powerpc | ||
| ppc | ||
| s390 | ||
| sh | ||
| sh64 | ||
| sparc | ||
| sparc64 | ||
| um | ||
| v850 | ||
| x86_64 | ||
| xtensa | ||