On Fri, 2008-05-09 at 15:26 +0900, Hidetoshi Seto wrote:
> [Bug-fix for "[BUG?][2.6.25-mm1] sleeping during IRQ disabled"]
>
> 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
>
> Reported-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
> Signed-off-by: Hidetoshi Seto <seto.hidetoshi@xxxxxxxxxxxxxx>
FWIW I like it this way.
Petr Tesarik
> ---
> arch/ia64/kernel/entry.S | 14 ++++++++++----
> arch/ia64/kernel/process.c | 25 +++++++++++++++++++++----
> 2 files changed, 31 insertions(+), 8 deletions(-)
>
> diff --git a/arch/ia64/kernel/entry.S b/arch/ia64/kernel/entry.S
> index e49ad8c..ef6b031 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
> @@ -1170,8 +1173,8 @@ skip_rbs_switch:
> (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
> rsm psr.i // disable interrupts
> @@ -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/process.c b/arch/ia64/kernel/process.c
> index 58dcfac..a3a34b4 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_resume_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;
>
> --
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