From 02c88d142ea6e64b0f81dcf3687a889d8a3556ba Mon Sep 17 00:00:00 2001 From: Vineet Gupta Date: Tue, 14 May 2019 14:35:45 -0700 Subject: [PATCH] ARC: mm: do_page_fault refactor #4: consolidate retry related logic stats update code can now elide "retry" check and additional level of indentation since all retry handling is done ahead of it already Signed-off-by: Vineet Gupta --- arch/arc/mm/fault.c | 60 +++++++++++++++++++++++---------------------- 1 file changed, 31 insertions(+), 29 deletions(-) diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c index 8c7c81ce7f6a..4597b4886edd 100644 --- a/arch/arc/mm/fault.c +++ b/arch/arc/mm/fault.c @@ -65,8 +65,8 @@ void do_page_fault(unsigned long address, struct pt_regs *regs) struct mm_struct *mm = tsk->mm; int si_code = SEGV_MAPERR; unsigned int write = 0, exec = 0, mask; - vm_fault_t fault; - unsigned int flags; + vm_fault_t fault; /* handle_mm_fault() output */ + unsigned int flags; /* handle_mm_fault() input */ /* * NOTE! We MUST NOT take any locks for this case. We may @@ -125,49 +125,51 @@ retry: goto bad_area; } - /* - * If for any reason at all we couldn't handle the fault, - * make sure we exit gracefully rather than endlessly redo - * the fault. - */ fault = handle_mm_fault(vma, address, flags); - if (fatal_signal_pending(current)) { + /* + * Fault retry nuances + */ + if (unlikely(fault & VM_FAULT_RETRY)) { /* - * if fault retry, mmap_sem already relinquished by core mm - * so OK to return to user mode (with signal handled first) + * If fault needs to be retried, handle any pending signals + * first (by returning to user mode). + * mmap_sem already relinquished by core mm for RETRY case */ - if (fault & VM_FAULT_RETRY) { + if (fatal_signal_pending(current)) { if (!user_mode(regs)) goto no_context; return; } + /* + * retry state machine + */ + if (flags & FAULT_FLAG_ALLOW_RETRY) { + flags &= ~FAULT_FLAG_ALLOW_RETRY; + flags |= FAULT_FLAG_TRIED; + goto retry; + } } + /* + * Major/minor page fault accounting + * (in case of retry we only land here once) + */ perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); if (likely(!(fault & VM_FAULT_ERROR))) { - if (flags & FAULT_FLAG_ALLOW_RETRY) { - /* To avoid updating stats twice for retry case */ - if (fault & VM_FAULT_MAJOR) { - tsk->maj_flt++; - perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, - regs, address); - } else { - tsk->min_flt++; - perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, - regs, address); - } - - if (fault & VM_FAULT_RETRY) { - flags &= ~FAULT_FLAG_ALLOW_RETRY; - flags |= FAULT_FLAG_TRIED; - goto retry; - } + if (fault & VM_FAULT_MAJOR) { + tsk->maj_flt++; + perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, + regs, address); + } else { + tsk->min_flt++; + perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, + regs, address); } - /* Fault Handled Gracefully */ + /* Normal return path: fault Handled Gracefully */ up_read(&mm->mmap_sem); return; } -- 2.30.2