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ARC: mm: do_page_fault refactor #4: consolidate retry related logic

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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 <vgupta@synopsys.com>
This commit is contained in:
Vineet Gupta 2019-05-14 14:35:45 -07:00
parent 85c5e33763
commit 02c88d142e
1 changed files with 31 additions and 29 deletions
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60
arch/arc/mm/fault.c
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@ -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 @@ void do_page_fault(unsigned long address, struct pt_regs *regs)
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;
}