I realized this while having a map containing both a struct bpf_timer and a struct bpf_wq: the third argument provided to the bpf_wq callback is not the struct bpf_wq pointer itself, but the pointer to the value in the map.
Which means that the users need to double cast the provided "value" as this is not a struct bpf_wq *.
This is a change of API, but there doesn't seem to be much users of bpf_wq right now, so we should be able to go with this right now.
Signed-off-by: Benjamin Tissoires bentiss@kernel.org --- Changes in v2: - amended the selftests to retrieve something from the third argument of the callback - Link to v1: https://lore.kernel.org/r/20240705-fix-wq-v1-0-91b4d82cd825@kernel.org
--- Benjamin Tissoires (2): bpf: helpers: fix bpf_wq_set_callback_impl signature selftests/bpf: amend for wrong bpf_wq_set_callback_impl signature
kernel/bpf/helpers.c | 2 +- tools/testing/selftests/bpf/bpf_experimental.h | 2 +- tools/testing/selftests/bpf/progs/wq.c | 19 ++++++++++++++----- tools/testing/selftests/bpf/progs/wq_failures.c | 4 ++-- 4 files changed, 18 insertions(+), 9 deletions(-) --- base-commit: fd8db07705c55a995c42b1e71afc42faad675b0b change-id: 20240705-fix-wq-f069c7fb36c3
Best regards,
I realized this while having a map containing both a struct bpf_timer and a struct bpf_wq: the third argument provided to the bpf_wq callback is not the struct bpf_wq pointer itself, but the pointer to the value in the map.
Which means that the users need to double cast the provided "value" as this is not a struct bpf_wq *.
This is a change of API, but there doesn't seem to be much users of bpf_wq right now, so we should be able to go with this right now.
Fixes: 81f1d7a583fa ("bpf: wq: add bpf_wq_set_callback_impl") Signed-off-by: Benjamin Tissoires bentiss@kernel.org --- kernel/bpf/helpers.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 229396172026..5241ba671c5a 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -2734,7 +2734,7 @@ __bpf_kfunc int bpf_wq_start(struct bpf_wq *wq, unsigned int flags) }
__bpf_kfunc int bpf_wq_set_callback_impl(struct bpf_wq *wq, - int (callback_fn)(void *map, int *key, struct bpf_wq *wq), + int (callback_fn)(void *map, int *key, void *value), unsigned int flags, void *aux__ign) {
See the previous patch: the API was wrong, we were provided the pointer to the value, not the actual struct bpf_wq *.
Signed-off-by: Benjamin Tissoires bentiss@kernel.org
---
changes in v2: - amended to retrieve something from the third argument of the callback --- tools/testing/selftests/bpf/bpf_experimental.h | 2 +- tools/testing/selftests/bpf/progs/wq.c | 19 ++++++++++++++----- tools/testing/selftests/bpf/progs/wq_failures.c | 4 ++-- 3 files changed, 17 insertions(+), 8 deletions(-)
diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing/selftests/bpf/bpf_experimental.h index eede6fc2ccb4..828556cdc2f0 100644 --- a/tools/testing/selftests/bpf/bpf_experimental.h +++ b/tools/testing/selftests/bpf/bpf_experimental.h @@ -552,7 +552,7 @@ extern void bpf_iter_css_destroy(struct bpf_iter_css *it) __weak __ksym; extern int bpf_wq_init(struct bpf_wq *wq, void *p__map, unsigned int flags) __weak __ksym; extern int bpf_wq_start(struct bpf_wq *wq, unsigned int flags) __weak __ksym; extern int bpf_wq_set_callback_impl(struct bpf_wq *wq, - int (callback_fn)(void *map, int *key, struct bpf_wq *wq), + int (callback_fn)(void *map, int *key, void *value), unsigned int flags__k, void *aux__ign) __ksym; #define bpf_wq_set_callback(timer, cb, flags) \ bpf_wq_set_callback_impl(timer, cb, flags, NULL) diff --git a/tools/testing/selftests/bpf/progs/wq.c b/tools/testing/selftests/bpf/progs/wq.c index 49e712acbf60..f8d3ae0c29ae 100644 --- a/tools/testing/selftests/bpf/progs/wq.c +++ b/tools/testing/selftests/bpf/progs/wq.c @@ -32,6 +32,7 @@ struct { } hmap_malloc SEC(".maps");
struct elem { + int ok_offset; struct bpf_wq w; };
@@ -53,7 +54,7 @@ __u32 ok; __u32 ok_sleepable;
static int test_elem_callback(void *map, int *key, - int (callback_fn)(void *map, int *key, struct bpf_wq *wq)) + int (callback_fn)(void *map, int *key, void *value)) { struct elem init = {}, *val; struct bpf_wq *wq; @@ -70,6 +71,8 @@ static int test_elem_callback(void *map, int *key, if (!val) return -2;
+ val->ok_offset = *key; + wq = &val->w; if (bpf_wq_init(wq, map, 0) != 0) return -3; @@ -84,7 +87,7 @@ static int test_elem_callback(void *map, int *key, }
static int test_hmap_elem_callback(void *map, int *key, - int (callback_fn)(void *map, int *key, struct bpf_wq *wq)) + int (callback_fn)(void *map, int *key, void *value)) { struct hmap_elem init = {}, *val; struct bpf_wq *wq; @@ -114,7 +117,7 @@ static int test_hmap_elem_callback(void *map, int *key, }
/* callback for non sleepable workqueue */ -static int wq_callback(void *map, int *key, struct bpf_wq *work) +static int wq_callback(void *map, int *key, void *value) { bpf_kfunc_common_test(); ok |= (1 << *key); @@ -122,10 +125,16 @@ static int wq_callback(void *map, int *key, struct bpf_wq *work) }
/* callback for sleepable workqueue */ -static int wq_cb_sleepable(void *map, int *key, struct bpf_wq *work) +static int wq_cb_sleepable(void *map, int *key, void *value) { + struct elem *data = (struct elem *)value; + int offset = data->ok_offset; + + if (*key != offset) + return 0; + bpf_kfunc_call_test_sleepable(); - ok_sleepable |= (1 << *key); + ok_sleepable |= (1 << offset); return 0; }
diff --git a/tools/testing/selftests/bpf/progs/wq_failures.c b/tools/testing/selftests/bpf/progs/wq_failures.c index 4cbdb425f223..25b51a72fe0f 100644 --- a/tools/testing/selftests/bpf/progs/wq_failures.c +++ b/tools/testing/selftests/bpf/progs/wq_failures.c @@ -28,14 +28,14 @@ struct { } lru SEC(".maps");
/* callback for non sleepable workqueue */ -static int wq_callback(void *map, int *key, struct bpf_wq *work) +static int wq_callback(void *map, int *key, void *value) { bpf_kfunc_common_test(); return 0; }
/* callback for sleepable workqueue */ -static int wq_cb_sleepable(void *map, int *key, struct bpf_wq *work) +static int wq_cb_sleepable(void *map, int *key, void *value) { bpf_kfunc_call_test_sleepable(); return 0;
Hello:
This series was applied to bpf/bpf-next.git (master) by Alexei Starovoitov ast@kernel.org:
On Mon, 08 Jul 2024 11:52:56 +0200 you wrote:
I realized this while having a map containing both a struct bpf_timer and a struct bpf_wq: the third argument provided to the bpf_wq callback is not the struct bpf_wq pointer itself, but the pointer to the value in the map.
Which means that the users need to double cast the provided "value" as this is not a struct bpf_wq *.
[...]
Here is the summary with links: - [bpf-next,v2,1/2] bpf: helpers: fix bpf_wq_set_callback_impl signature https://git.kernel.org/bpf/bpf-next/c/f56f4d541eab - [bpf-next,v2,2/2] selftests/bpf: amend for wrong bpf_wq_set_callback_impl signature https://git.kernel.org/bpf/bpf-next/c/16e86f2e8199
You are awesome, thank you!
linux-kselftest-mirror@lists.linaro.org
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Benjamin Tissoires -
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