| Message ID | 20240425-bpf-next-v1-2-1d8330e6c643@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | bpf_wq followup series | expand |
On Thu, Apr 25, 2024 at 6:59 AM Benjamin Tissoires <bentiss@kernel.org> wrote: > > If someone stores both a timer and a workqueue in a hash map, on free, we > would walk it twice. > Add a check in htab_free_malloced_timers_or_wq and free the timers > and workqueues if they are present. > > Fixes: 246331e3f1ea ("bpf: allow struct bpf_wq to be embedded in arraymaps and hashmaps") > Signed-off-by: Benjamin Tissoires <bentiss@kernel.org> > --- > kernel/bpf/hashtab.c | 16 +++++----------- > 1 file changed, 5 insertions(+), 11 deletions(-) > > diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c > index 0179183c543a..20162ae741e9 100644 > --- a/kernel/bpf/hashtab.c > +++ b/kernel/bpf/hashtab.c > @@ -1515,7 +1515,7 @@ static void delete_all_elements(struct bpf_htab *htab) > migrate_enable(); > } > > -static void htab_free_malloced_timers_or_wq(struct bpf_htab *htab, bool is_timer) > +static void htab_free_malloced_timers_or_wq(struct bpf_htab *htab) > { > int i; > > @@ -1527,10 +1527,10 @@ static void htab_free_malloced_timers_or_wq(struct bpf_htab *htab, bool is_timer > > hlist_nulls_for_each_entry(l, n, head, hash_node) { > /* We only free timer on uref dropping to zero */ > - if (is_timer) > + if (btf_record_has_field(htab->map.record, BPF_TIMER)) > bpf_obj_free_timer(htab->map.record, > l->key + round_up(htab->map.key_size, 8)); > - else > + if (btf_record_has_field(htab->map.record, BPF_WORKQUEUE)) > bpf_obj_free_workqueue(htab->map.record, > l->key + round_up(htab->map.key_size, 8)); > } > @@ -1544,18 +1544,12 @@ static void htab_map_free_timers_and_wq(struct bpf_map *map) > struct bpf_htab *htab = container_of(map, struct bpf_htab, map); > > /* We only free timer and workqueue on uref dropping to zero */ > - if (btf_record_has_field(htab->map.record, BPF_TIMER)) { > + if (btf_record_has_field(htab->map.record, BPF_TIMER | BPF_WORKQUEUE)) { > if (!htab_is_prealloc(htab)) > - htab_free_malloced_timers_or_wq(htab, true); > + htab_free_malloced_timers_or_wq(htab); > else > htab_free_prealloced_timers(htab); > } > - if (btf_record_has_field(htab->map.record, BPF_WORKQUEUE)) { > - if (!htab_is_prealloc(htab)) > - htab_free_malloced_timers_or_wq(htab, false); > - else > - htab_free_prealloced_wq(htab); This looks wrong. htab_free_prealloced_wq() is now unused as compiler says: ../kernel/bpf/hashtab.c:243:13: warning: ‘htab_free_prealloced_wq’ defined but not used [-Wunused-function] 243 | static void htab_free_prealloced_wq(struct bpf_htab *htab) | ^~~~~~~~~~~~~~~~~~~~~~~ and prealloced maps with wq leak wq-s. pw-bot: cr
Hi Benjamin,
kernel test robot noticed the following build warnings:
[auto build test WARNING on 52578f7f53ff8fe3a8f6f3bc8b5956615c07a16e]
url: https://github.com/intel-lab-lkp/linux/commits/Benjamin-Tissoires/bpf-do-not-walk-twice-the-map-on-free/20240425-220322
base: 52578f7f53ff8fe3a8f6f3bc8b5956615c07a16e
patch link: https://lore.kernel.org/r/20240425-bpf-next-v1-2-1d8330e6c643%40kernel.org
patch subject: [PATCH 2/3] bpf: do not walk twice the hash map on free
config: arc-randconfig-002-20240426 (https://download.01.org/0day-ci/archive/20240426/202404260653.ULrCGrp2-lkp@intel.com/config)
compiler: arc-elf-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240426/202404260653.ULrCGrp2-lkp@intel.com/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 <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202404260653.ULrCGrp2-lkp@intel.com/
All warnings (new ones prefixed by >>):
>> kernel/bpf/hashtab.c:243:13: warning: 'htab_free_prealloced_wq' defined but not used [-Wunused-function]
243 | static void htab_free_prealloced_wq(struct bpf_htab *htab)
| ^~~~~~~~~~~~~~~~~~~~~~~
vim +/htab_free_prealloced_wq +243 kernel/bpf/hashtab.c
68134668c17f31 Alexei Starovoitov 2021-07-14 242
246331e3f1eac9 Benjamin Tissoires 2024-04-20 @243 static void htab_free_prealloced_wq(struct bpf_htab *htab)
246331e3f1eac9 Benjamin Tissoires 2024-04-20 244 {
246331e3f1eac9 Benjamin Tissoires 2024-04-20 245 u32 num_entries = htab->map.max_entries;
246331e3f1eac9 Benjamin Tissoires 2024-04-20 246 int i;
246331e3f1eac9 Benjamin Tissoires 2024-04-20 247
246331e3f1eac9 Benjamin Tissoires 2024-04-20 248 if (!btf_record_has_field(htab->map.record, BPF_WORKQUEUE))
246331e3f1eac9 Benjamin Tissoires 2024-04-20 249 return;
246331e3f1eac9 Benjamin Tissoires 2024-04-20 250 if (htab_has_extra_elems(htab))
246331e3f1eac9 Benjamin Tissoires 2024-04-20 251 num_entries += num_possible_cpus();
246331e3f1eac9 Benjamin Tissoires 2024-04-20 252
246331e3f1eac9 Benjamin Tissoires 2024-04-20 253 for (i = 0; i < num_entries; i++) {
246331e3f1eac9 Benjamin Tissoires 2024-04-20 254 struct htab_elem *elem;
246331e3f1eac9 Benjamin Tissoires 2024-04-20 255
246331e3f1eac9 Benjamin Tissoires 2024-04-20 256 elem = get_htab_elem(htab, i);
246331e3f1eac9 Benjamin Tissoires 2024-04-20 257 bpf_obj_free_workqueue(htab->map.record,
246331e3f1eac9 Benjamin Tissoires 2024-04-20 258 elem->key + round_up(htab->map.key_size, 8));
246331e3f1eac9 Benjamin Tissoires 2024-04-20 259 cond_resched();
246331e3f1eac9 Benjamin Tissoires 2024-04-20 260 }
246331e3f1eac9 Benjamin Tissoires 2024-04-20 261 }
246331e3f1eac9 Benjamin Tissoires 2024-04-20 262
On Apr 25 2024, Alexei Starovoitov wrote: > On Thu, Apr 25, 2024 at 6:59 AM Benjamin Tissoires <bentiss@kernel.org> wrote: > > > > If someone stores both a timer and a workqueue in a hash map, on free, we > > would walk it twice. > > Add a check in htab_free_malloced_timers_or_wq and free the timers > > and workqueues if they are present. > > > > Fixes: 246331e3f1ea ("bpf: allow struct bpf_wq to be embedded in arraymaps and hashmaps") > > Signed-off-by: Benjamin Tissoires <bentiss@kernel.org> > > --- > > kernel/bpf/hashtab.c | 16 +++++----------- > > 1 file changed, 5 insertions(+), 11 deletions(-) > > > > diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c > > index 0179183c543a..20162ae741e9 100644 > > --- a/kernel/bpf/hashtab.c > > +++ b/kernel/bpf/hashtab.c > > @@ -1515,7 +1515,7 @@ static void delete_all_elements(struct bpf_htab *htab) > > migrate_enable(); > > } > > > > -static void htab_free_malloced_timers_or_wq(struct bpf_htab *htab, bool is_timer) > > +static void htab_free_malloced_timers_or_wq(struct bpf_htab *htab) > > { > > int i; > > > > @@ -1527,10 +1527,10 @@ static void htab_free_malloced_timers_or_wq(struct bpf_htab *htab, bool is_timer > > > > hlist_nulls_for_each_entry(l, n, head, hash_node) { > > /* We only free timer on uref dropping to zero */ > > - if (is_timer) > > + if (btf_record_has_field(htab->map.record, BPF_TIMER)) > > bpf_obj_free_timer(htab->map.record, > > l->key + round_up(htab->map.key_size, 8)); > > - else > > + if (btf_record_has_field(htab->map.record, BPF_WORKQUEUE)) > > bpf_obj_free_workqueue(htab->map.record, > > l->key + round_up(htab->map.key_size, 8)); > > } > > @@ -1544,18 +1544,12 @@ static void htab_map_free_timers_and_wq(struct bpf_map *map) > > struct bpf_htab *htab = container_of(map, struct bpf_htab, map); > > > > /* We only free timer and workqueue on uref dropping to zero */ > > - if (btf_record_has_field(htab->map.record, BPF_TIMER)) { > > + if (btf_record_has_field(htab->map.record, BPF_TIMER | BPF_WORKQUEUE)) { > > if (!htab_is_prealloc(htab)) > > - htab_free_malloced_timers_or_wq(htab, true); > > + htab_free_malloced_timers_or_wq(htab); > > else > > htab_free_prealloced_timers(htab); > > } > > - if (btf_record_has_field(htab->map.record, BPF_WORKQUEUE)) { > > - if (!htab_is_prealloc(htab)) > > - htab_free_malloced_timers_or_wq(htab, false); > > - else > > - htab_free_prealloced_wq(htab); > > This looks wrong. > htab_free_prealloced_wq() is now unused as compiler says: > ../kernel/bpf/hashtab.c:243:13: warning: ‘htab_free_prealloced_wq’ > defined but not used [-Wunused-function] > 243 | static void htab_free_prealloced_wq(struct bpf_htab *htab) > | ^~~~~~~~~~~~~~~~~~~~~~~ > > and prealloced maps with wq leak wq-s. oops, you are right. Sending a v2 right away (sorry for the delay). Cheers, Benjamin
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index 0179183c543a..20162ae741e9 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -1515,7 +1515,7 @@ static void delete_all_elements(struct bpf_htab *htab) migrate_enable(); } -static void htab_free_malloced_timers_or_wq(struct bpf_htab *htab, bool is_timer) +static void htab_free_malloced_timers_or_wq(struct bpf_htab *htab) { int i; @@ -1527,10 +1527,10 @@ static void htab_free_malloced_timers_or_wq(struct bpf_htab *htab, bool is_timer hlist_nulls_for_each_entry(l, n, head, hash_node) { /* We only free timer on uref dropping to zero */ - if (is_timer) + if (btf_record_has_field(htab->map.record, BPF_TIMER)) bpf_obj_free_timer(htab->map.record, l->key + round_up(htab->map.key_size, 8)); - else + if (btf_record_has_field(htab->map.record, BPF_WORKQUEUE)) bpf_obj_free_workqueue(htab->map.record, l->key + round_up(htab->map.key_size, 8)); } @@ -1544,18 +1544,12 @@ static void htab_map_free_timers_and_wq(struct bpf_map *map) struct bpf_htab *htab = container_of(map, struct bpf_htab, map); /* We only free timer and workqueue on uref dropping to zero */ - if (btf_record_has_field(htab->map.record, BPF_TIMER)) { + if (btf_record_has_field(htab->map.record, BPF_TIMER | BPF_WORKQUEUE)) { if (!htab_is_prealloc(htab)) - htab_free_malloced_timers_or_wq(htab, true); + htab_free_malloced_timers_or_wq(htab); else htab_free_prealloced_timers(htab); } - if (btf_record_has_field(htab->map.record, BPF_WORKQUEUE)) { - if (!htab_is_prealloc(htab)) - htab_free_malloced_timers_or_wq(htab, false); - else - htab_free_prealloced_wq(htab); - } } /* Called when map->refcnt goes to zero, either from workqueue or from syscall */
If someone stores both a timer and a workqueue in a hash map, on free, we would walk it twice. Add a check in htab_free_malloced_timers_or_wq and free the timers and workqueues if they are present. Fixes: 246331e3f1ea ("bpf: allow struct bpf_wq to be embedded in arraymaps and hashmaps") Signed-off-by: Benjamin Tissoires <bentiss@kernel.org> --- kernel/bpf/hashtab.c | 16 +++++----------- 1 file changed, 5 insertions(+), 11 deletions(-)