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> |
||
|---|---|---|
| .. | ||
| boot | ||
| kernel | ||
| lib | ||
| m32104ut | ||
| m32700ut | ||
| mappi | ||
| mappi2 | ||
| mappi3 | ||
| mm | ||
| oaks32r | ||
| oprofile | ||
| opsput | ||
| defconfig | ||
| Kconfig | ||
| Kconfig.debug | ||
| Makefile | ||