The do / while (slot_nr >= UINSNS_PER_PAGE) loop in xol_take_insn_slot() makes no sense, the checked condition is always true. Change this code to use the "for (;;)" loop, this way we do not need to change slot_nr if test_and_set_bit() fails.
Also, kill the unnecessary xol_vaddr != NULL check in xol_get_insn_slot(), xol_take_insn_slot() never returns NULL. Signed-off-by: Oleg Nesterov <[email protected]> --- kernel/events/uprobes.c | 17 ++++------------- 1 file changed, 4 insertions(+), 13 deletions(-) diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 4619de10772e..bfe106ecad38 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -1631,25 +1631,20 @@ void uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm) */ static unsigned long xol_take_insn_slot(struct xol_area *area) { - unsigned long slot_addr; - int slot_nr; + unsigned int slot_nr; - do { + for (;;) { slot_nr = find_first_zero_bit(area->bitmap, UINSNS_PER_PAGE); if (slot_nr < UINSNS_PER_PAGE) { if (!test_and_set_bit(slot_nr, area->bitmap)) break; - - slot_nr = UINSNS_PER_PAGE; continue; } wait_event(area->wq, (atomic_read(&area->slot_count) < UINSNS_PER_PAGE)); - } while (slot_nr >= UINSNS_PER_PAGE); + } - slot_addr = area->vaddr + (slot_nr * UPROBE_XOL_SLOT_BYTES); atomic_inc(&area->slot_count); - - return slot_addr; + return area->vaddr + slot_nr * UPROBE_XOL_SLOT_BYTES; } /* @@ -1666,12 +1661,8 @@ static unsigned long xol_get_insn_slot(struct uprobe *uprobe) return 0; xol_vaddr = xol_take_insn_slot(area); - if (unlikely(!xol_vaddr)) - return 0; - arch_uprobe_copy_ixol(area->page, xol_vaddr, &uprobe->arch.ixol, sizeof(uprobe->arch.ixol)); - return xol_vaddr; } -- 2.25.1.362.g51ebf55
