On Tue, Jun 25, 2024 at 11:03 PM kernel test robot <[email protected]> wrote:
>
> Hi Andrii,
>
> kernel test robot noticed the following build warnings:
>
> [auto build test WARNING on next-20240624]
> [also build test WARNING on v6.10-rc5]
> [cannot apply to perf-tools-next/perf-tools-next tip/perf/core
> perf-tools/perf-tools linus/master acme/perf/core v6.10-rc5 v6.10-rc4
> v6.10-rc3]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch#_base_tree_information]
>
> url:
> https://github.com/intel-lab-lkp/linux/commits/Andrii-Nakryiko/uprobes-update-outdated-comment/20240626-001728
> base: next-20240624
> patch link:
> https://lore.kernel.org/r/20240625002144.3485799-5-andrii%40kernel.org
> patch subject: [PATCH 04/12] uprobes: revamp uprobe refcounting and lifetime
> management
> config: x86_64-defconfig
> (https://download.01.org/0day-ci/archive/20240626/[email protected]/config)
> compiler: gcc-13 (Ubuntu 13.2.0-4ubuntu3) 13.2.0
> reproduce (this is a W=1 build):
> (https://download.01.org/0day-ci/archive/20240626/[email protected]/reproduce)
>
> If you fix the issue in a separate patch/commit (i.e. not just a new version
> of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <[email protected]>
> | Closes:
> https://lore.kernel.org/oe-kbuild-all/[email protected]/
>
> All warnings (new ones prefixed by >>):
>
> >> kernel/events/uprobes.c:638: warning: Function parameter or struct member
> >> 'uprobe' not described in '__get_uprobe'
> >> kernel/events/uprobes.c:638: warning: expecting prototype for Caller has
> >> to make sure that(). Prototype was for __get_uprobe() instead
>
>
> vim +638 kernel/events/uprobes.c
>
> b9adadbcb8dfc8 Andrii Nakryiko 2024-06-24 625
> b9adadbcb8dfc8 Andrii Nakryiko 2024-06-24 626 /**
I shouldn't have used /** here, I'll fix this.
> b9adadbcb8dfc8 Andrii Nakryiko 2024-06-24 627 * Caller has to make sure
> that:
> b9adadbcb8dfc8 Andrii Nakryiko 2024-06-24 628 * a) either uprobe's
> refcnt is positive before this call;
> b9adadbcb8dfc8 Andrii Nakryiko 2024-06-24 629 * b) or uprobes_treelock
> is held (doesn't matter if for read or write),
> b9adadbcb8dfc8 Andrii Nakryiko 2024-06-24 630 * preventing uprobe's
> destructor from removing it from uprobes_tree.
> b9adadbcb8dfc8 Andrii Nakryiko 2024-06-24 631 *
> b9adadbcb8dfc8 Andrii Nakryiko 2024-06-24 632 * In the latter case,
> uprobe's destructor will "resurrect" uprobe instance if
> b9adadbcb8dfc8 Andrii Nakryiko 2024-06-24 633 * it detects that its
> refcount went back to being positive again inbetween it
> b9adadbcb8dfc8 Andrii Nakryiko 2024-06-24 634 * dropping to zero at some
> point and (potentially delayed) destructor
> b9adadbcb8dfc8 Andrii Nakryiko 2024-06-24 635 * callback actually running.
> b9adadbcb8dfc8 Andrii Nakryiko 2024-06-24 636 */
> b9adadbcb8dfc8 Andrii Nakryiko 2024-06-24 637 static struct uprobe
> *__get_uprobe(struct uprobe *uprobe)
> f231722a2b27ee Oleg Nesterov 2015-07-21 @638 {
> b9adadbcb8dfc8 Andrii Nakryiko 2024-06-24 639 s64 v;
> b9adadbcb8dfc8 Andrii Nakryiko 2024-06-24 640
> b9adadbcb8dfc8 Andrii Nakryiko 2024-06-24 641 v =
> atomic64_add_return(UPROBE_REFCNT_GET, &uprobe->ref);
> b9adadbcb8dfc8 Andrii Nakryiko 2024-06-24 642
> b9adadbcb8dfc8 Andrii Nakryiko 2024-06-24 643 /*
> b9adadbcb8dfc8 Andrii Nakryiko 2024-06-24 644 * If the highest bit
> is set, we need to clear it. If cmpxchg() fails,
> b9adadbcb8dfc8 Andrii Nakryiko 2024-06-24 645 * we don't retry
> because there is another CPU that just managed to
> b9adadbcb8dfc8 Andrii Nakryiko 2024-06-24 646 * update refcnt and
> will attempt the same "fix up". Eventually one of
> b9adadbcb8dfc8 Andrii Nakryiko 2024-06-24 647 * them will succeed
> to clear highset bit.
> b9adadbcb8dfc8 Andrii Nakryiko 2024-06-24 648 */
> b9adadbcb8dfc8 Andrii Nakryiko 2024-06-24 649 if (unlikely(v < 0))
> b9adadbcb8dfc8 Andrii Nakryiko 2024-06-24 650
> (void)atomic64_cmpxchg(&uprobe->ref, v, v & ~(1ULL << 63));
> b9adadbcb8dfc8 Andrii Nakryiko 2024-06-24 651
> f231722a2b27ee Oleg Nesterov 2015-07-21 652 return uprobe;
> f231722a2b27ee Oleg Nesterov 2015-07-21 653 }
> f231722a2b27ee Oleg Nesterov 2015-07-21 654
>
> --
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests/wiki
