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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| .. | ||
| align.c | ||
| asm-offsets.c | ||
| entry.S | ||
| head.S | ||
| init_task.c | ||
| io_m32104ut.c | ||
| io_m32700ut.c | ||
| io_mappi2.c | ||
| io_mappi3.c | ||
| io_mappi.c | ||
| io_oaks32r.c | ||
| io_opsput.c | ||
| io_usrv.c | ||
| irq.c | ||
| m32r_ksyms.c | ||
| Makefile | ||
| module.c | ||
| process.c | ||
| ptrace.c | ||
| semaphore.c | ||
| setup_m32104ut.c | ||
| setup_m32700ut.c | ||
| setup_mappi2.c | ||
| setup_mappi3.c | ||
| setup_mappi.c | ||
| setup_oaks32r.c | ||
| setup_opsput.c | ||
| setup_usrv.c | ||
| setup.c | ||
| signal.c | ||
| smp.c | ||
| smpboot.c | ||
| sys_m32r.c | ||
| time.c | ||
| traps.c | ||
| vmlinux.lds.S | ||