Tony-san, How about this patch as a draft? This patch does: - enable interrupts before calling schedule() as same as others, ex. x86 - enable interrupts during ia64_do_signal() and ia64_sync_krbs() - do_notify_resume_user() is still called with interrupts disabled, since we can take short path of fsys_mode if-statement quickly. - pfm_handle_work() is also called with interrupts disabled, since it can deal interrupt mask within itself. - fix/add some comments/notes Signed-off-by: Hidetoshi Seto <seto.hidetoshi@xxxxxxxxxxxxxx> --- arch/ia64/kernel/entry.S | 26 ++++++++++++++++---------- arch/ia64/kernel/perfmon.c | 16 ++++++++++------ arch/ia64/kernel/process.c | 25 +++++++++++++++++++++---- 3 files changed, 47 insertions(+), 20 deletions(-) diff --git a/arch/ia64/kernel/entry.S b/arch/ia64/kernel/entry.S index e49ad8c..ca2bb95 100644 --- a/arch/ia64/kernel/entry.S +++ b/arch/ia64/kernel/entry.S @@ -1156,6 +1156,9 @@ skip_rbs_switch: * r31 = current->thread_info->flags * On exit: * p6 = TRUE if work-pending-check needs to be redone + * + * Interrupts are disabled on entry, reenabled depend on work, and + * disabled on exit. */ .work_pending_syscall: add r2=-8,r2 @@ -1164,16 +1167,16 @@ skip_rbs_switch: st8 [r2]=r8 st8 [r3]=r10 .work_pending: - tbit.z p6,p0=r31,TIF_NEED_RESCHED // current_thread_info()->need_resched==0? + tbit.z p6,p0=r31,TIF_NEED_RESCHED // is resched not needed? (p6) br.cond.sptk.few .notify #ifdef CONFIG_PREEMPT (pKStk) dep r21=-1,r0,PREEMPT_ACTIVE_BIT,1 ;; (pKStk) st4 [r20]=r21 - ssm psr.i // enable interrupts #endif + ssm psr.i // enable interrupts br.call.spnt.many rp=schedule -.ret9: cmp.eq p6,p0=r0,r0 // p6 <- 1 +.ret9: cmp.eq p6,p0=r0,r0 // p6 <- 1 (re-check) rsm psr.i // disable interrupts ;; #ifdef CONFIG_PREEMPT @@ -1182,13 +1185,13 @@ skip_rbs_switch: (pKStk) st4 [r20]=r0 // preempt_count() <- 0 #endif (pLvSys)br.cond.sptk.few .work_pending_syscall_end - br.cond.sptk.many .work_processed_kernel // re-check + br.cond.sptk.many .work_processed_kernel .notify: (pUStk) br.call.spnt.many rp=notify_resume_user -.ret10: cmp.ne p6,p0=r0,r0 // p6 <- 0 +.ret10: cmp.ne p6,p0=r0,r0 // p6 <- 0 (don't re-check) (pLvSys)br.cond.sptk.few .work_pending_syscall_end - br.cond.sptk.many .work_processed_kernel // don't re-check + br.cond.sptk.many .work_processed_kernel .work_pending_syscall_end: adds r2=PT(R8)+16,r12 @@ -1196,7 +1199,7 @@ skip_rbs_switch: ;; ld8 r8=[r2] ld8 r10=[r3] - br.cond.sptk.many .work_processed_syscall // re-check + br.cond.sptk.many .work_processed_syscall END(ia64_leave_kernel) @@ -1234,9 +1237,12 @@ GLOBAL_ENTRY(ia64_invoke_schedule_tail) END(ia64_invoke_schedule_tail) /* - * Setup stack and call do_notify_resume_user(). Note that pSys and pNonSys need to - * be set up by the caller. We declare 8 input registers so the system call - * args get preserved, in case we need to restart a system call. + * Setup stack and call do_notify_resume_user(), keeping interrupts + * disabled. + * + * Note that pSys and pNonSys need to be set up by the caller. + * We declare 8 input registers so the system call args get preserved, + * in case we need to restart a system call. */ ENTRY(notify_resume_user) .prologue ASM_UNW_PRLG_RP|ASM_UNW_PRLG_PFS, ASM_UNW_PRLG_GRSAVE(8) diff --git a/arch/ia64/kernel/perfmon.c b/arch/ia64/kernel/perfmon.c index c1ad27d..71d0513 100644 --- a/arch/ia64/kernel/perfmon.c +++ b/arch/ia64/kernel/perfmon.c @@ -5013,12 +5013,13 @@ pfm_context_force_terminate(pfm_context_t *ctx, struct pt_regs *regs) } static int pfm_ovfl_notify_user(pfm_context_t *ctx, unsigned long ovfl_pmds); + /* * pfm_handle_work() can be called with interrupts enabled * (TIF_NEED_RESCHED) or disabled. The down_interruptible * call may sleep, therefore we must re-enable interrupts * to avoid deadlocks. It is safe to do so because this function - * is called ONLY when returning to user level (PUStk=1), in which case + * is called ONLY when returning to user level (pUStk=1), in which case * there is no risk of kernel stack overflow due to deep * interrupt nesting. */ @@ -5034,7 +5035,8 @@ pfm_handle_work(void) ctx = PFM_GET_CTX(current); if (ctx == NULL) { - printk(KERN_ERR "perfmon: [%d] has no PFM context\n", task_pid_nr(current)); + printk(KERN_ERR "perfmon: [%d] has no PFM context\n", + task_pid_nr(current)); return; } @@ -5058,11 +5060,12 @@ pfm_handle_work(void) /* * must be done before we check for simple-reset mode */ - if (ctx->ctx_fl_going_zombie || ctx->ctx_state == PFM_CTX_ZOMBIE) goto do_zombie; - + if (ctx->ctx_fl_going_zombie || ctx->ctx_state == PFM_CTX_ZOMBIE) + goto do_zombie; //if (CTX_OVFL_NOBLOCK(ctx)) goto skip_blocking; - if (reason == PFM_TRAP_REASON_RESET) goto skip_blocking; + if (reason == PFM_TRAP_REASON_RESET) + goto skip_blocking; /* * restore interrupt mask to what it was on entry. @@ -5110,7 +5113,8 @@ do_zombie: /* * in case of interruption of down() we don't restart anything */ - if (ret < 0) goto nothing_to_do; + if (ret < 0) + goto nothing_to_do; skip_blocking: pfm_resume_after_ovfl(ctx, ovfl_regs, regs); diff --git a/arch/ia64/kernel/process.c b/arch/ia64/kernel/process.c index 58dcfac..c7d4885 100644 --- a/arch/ia64/kernel/process.c +++ b/arch/ia64/kernel/process.c @@ -167,11 +167,18 @@ void tsk_clear_notify_resume(struct task_struct *tsk) clear_ti_thread_flag(task_thread_info(tsk), TIF_NOTIFY_RESUME); } +/* + * do_notify_resume_user(): + * Called from notify_from_user at entry.S, with interrupts disabled. + */ void -do_notify_resume_user (sigset_t *unused, struct sigscratch *scr, long in_syscall) +do_notify_resume_user(sigset_t *unused, struct sigscratch *scr, long in_syscall) { if (fsys_mode(current, &scr->pt)) { - /* defer signal-handling etc. until we return to privilege-level 0. */ + /* + * defer signal-handling etc. until we return to + * privilege-level 0. + */ if (!ia64_psr(&scr->pt)->lp) ia64_psr(&scr->pt)->lp = 1; return; @@ -179,16 +186,26 @@ do_notify_resume_user (sigset_t *unused, struct sigscratch *scr, long in_syscall #ifdef CONFIG_PERFMON if (current->thread.pfm_needs_checking) + /* + * Note: pfm_handle_work() allow us to call it with interrupts + * disabled, and may enable interrupts within the function. + */ pfm_handle_work(); #endif /* deal with pending signal delivery */ - if (test_thread_flag(TIF_SIGPENDING)) + if (test_thread_flag(TIF_SIGPENDING)) { + local_irq_enable(); /* force interrupt enable */ ia64_do_signal(scr, in_syscall); + } /* copy user rbs to kernel rbs */ - if (unlikely(test_thread_flag(TIF_RESTORE_RSE))) + if (unlikely(test_thread_flag(TIF_RESTORE_RSE))) { + local_irq_enable(); /* force interrupt enable */ ia64_sync_krbs(); + } + + local_irq_disable(); /* force interrupt disable */ } static int pal_halt = 1; -- To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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