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| author | Oleg Nesterov <oleg@redhat.com> | 2024-09-29 16:42:44 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2024-10-07 09:28:44 +0200 |
| commit | 6ffe8c7d871b327d16ae6b6f1db4c8ecb0f15c64 (patch) | |
| tree | e56a538a57bb3b16855fcc864cfac9d7e707f973 | |
| parent | 430af825ba991730f8acc3c804a4aef82e9f7ff6 (diff) | |
| download | lwn-6ffe8c7d871b327d16ae6b6f1db4c8ecb0f15c64.tar.gz lwn-6ffe8c7d871b327d16ae6b6f1db4c8ecb0f15c64.zip | |
uprobes: simplify xol_take_insn_slot() and its caller
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 <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240929144244.GA9480@redhat.com
| -rw-r--r-- | kernel/events/uprobes.c | 17 |
1 files changed, 4 insertions, 13 deletions
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 03035a859a56..616b5ff3fd85 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -1628,25 +1628,20 @@ 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; } /* @@ -1663,12 +1658,8 @@ 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; } |