[PATCH bpf-next 1/5] bpf: Add bpf_cpumask_first_and() kfunc

[PATCH bpf-next 1/5] bpf: Add bpf_cpumask_first_and() kfunc

[David Vernet]

We currently provide bpf_cpumask_first(), bpf_cpumask_any(), and
bpf_cpumask_any_and() kfuncs. bpf_cpumask_any() and
bpf_cpumask_any_and() are confusing misnomers in that they actually just
call cpumask_first() and cpumask_first_and() respectively.

We'll replace them with bpf_cpumask_any_distribute() and
bpf_cpumask_any_distribute_and() kfuncs in a subsequent patch, so let's
ensure feature parity by adding a bpf_cpumask_first_and() kfunc to
account for bpf_cpumask_any_and() being removed.

Signed-off-by: David Vernet <void@manifault.com>
---
 kernel/bpf/cpumask.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/kernel/bpf/cpumask.c b/kernel/bpf/cpumask.c
index 7efdf5d770ca..9416c8ac8a04 100644
--- a/kernel/bpf/cpumask.c
+++ b/kernel/bpf/cpumask.c
@@ -131,6 +131,21 @@ __bpf_kfunc u32 bpf_cpumask_first_zero(const struct cpumask *cpumask)
 	return cpumask_first_zero(cpumask);
 }
 
+/**
+ * bpf_cpumask_first_and() - Return the index of the first nonzero bit from the
+ *			     AND of two cpumasks.
+ * @src1: The first cpumask.
+ * @src2: The second cpumask.
+ *
+ * Find the index of the first nonzero bit of the AND of two cpumasks.
+ * struct bpf_cpumask pointers may be safely passed to @src1 and @src2.
+ */
+__bpf_kfunc u32 bpf_cpumask_first_and(const struct cpumask *src1,
+				      const struct cpumask *src2)
+{
+	return cpumask_first_and(src1, src2);
+}
+
 /**
  * bpf_cpumask_set_cpu() - Set a bit for a CPU in a BPF cpumask.
  * @cpu: The CPU to be set in the cpumask.
@@ -406,6 +421,7 @@ BTF_ID_FLAGS(func, bpf_cpumask_release, KF_RELEASE)
 BTF_ID_FLAGS(func, bpf_cpumask_acquire, KF_ACQUIRE | KF_TRUSTED_ARGS)
 BTF_ID_FLAGS(func, bpf_cpumask_first, KF_RCU)
 BTF_ID_FLAGS(func, bpf_cpumask_first_zero, KF_RCU)
+BTF_ID_FLAGS(func, bpf_cpumask_first_and, KF_RCU)
 BTF_ID_FLAGS(func, bpf_cpumask_set_cpu, KF_RCU)
 BTF_ID_FLAGS(func, bpf_cpumask_clear_cpu, KF_RCU)
 BTF_ID_FLAGS(func, bpf_cpumask_test_cpu, KF_RCU)
-- 
2.40.1

[PATCH bpf-next 2/5] selftests/bpf: Add test for new bpf_cpumask_first_and() kfunc

[David Vernet]

A prior patch added a new kfunc called bpf_cpumask_first_and() which
wraps cpumask_first_and(). This patch adds a selftest to validate its
behavior.

Signed-off-by: David Vernet <void@manifault.com>
---
 .../selftests/bpf/prog_tests/cpumask.c        |  1 +
 .../selftests/bpf/progs/cpumask_common.h      |  2 ++
 .../selftests/bpf/progs/cpumask_success.c     | 32 +++++++++++++++++++
 3 files changed, 35 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/cpumask.c b/tools/testing/selftests/bpf/prog_tests/cpumask.c
index d89191440fb1..756ea8b590b6 100644
--- a/tools/testing/selftests/bpf/prog_tests/cpumask.c
+++ b/tools/testing/selftests/bpf/prog_tests/cpumask.c
@@ -10,6 +10,7 @@ static const char * const cpumask_success_testcases[] = {
 	"test_set_clear_cpu",
 	"test_setall_clear_cpu",
 	"test_first_firstzero_cpu",
+	"test_firstand_nocpu",
 	"test_test_and_set_clear",
 	"test_and_or_xor",
 	"test_intersects_subset",
diff --git a/tools/testing/selftests/bpf/progs/cpumask_common.h b/tools/testing/selftests/bpf/progs/cpumask_common.h
index 0c5b785a93e4..b3493d5d263e 100644
--- a/tools/testing/selftests/bpf/progs/cpumask_common.h
+++ b/tools/testing/selftests/bpf/progs/cpumask_common.h
@@ -28,6 +28,8 @@ void bpf_cpumask_release(struct bpf_cpumask *cpumask) __ksym;
 struct bpf_cpumask *bpf_cpumask_acquire(struct bpf_cpumask *cpumask) __ksym;
 u32 bpf_cpumask_first(const struct cpumask *cpumask) __ksym;
 u32 bpf_cpumask_first_zero(const struct cpumask *cpumask) __ksym;
+u32 bpf_cpumask_first_and(const struct cpumask *src1,
+			  const struct cpumask *src2) __ksym;
 void bpf_cpumask_set_cpu(u32 cpu, struct bpf_cpumask *cpumask) __ksym;
 void bpf_cpumask_clear_cpu(u32 cpu, struct bpf_cpumask *cpumask) __ksym;
 bool bpf_cpumask_test_cpu(u32 cpu, const struct cpumask *cpumask) __ksym;
diff --git a/tools/testing/selftests/bpf/progs/cpumask_success.c b/tools/testing/selftests/bpf/progs/cpumask_success.c
index 602a88b03dbc..fbaf510f4ab5 100644
--- a/tools/testing/selftests/bpf/progs/cpumask_success.c
+++ b/tools/testing/selftests/bpf/progs/cpumask_success.c
@@ -175,6 +175,38 @@ int BPF_PROG(test_first_firstzero_cpu, struct task_struct *task, u64 clone_flags
 	return 0;
 }
 
+SEC("tp_btf/task_newtask")
+int BPF_PROG(test_firstand_nocpu, struct task_struct *task, u64 clone_flags)
+{
+	struct bpf_cpumask *mask1, *mask2;
+	u32 first;
+
+	if (!is_test_task())
+		return 0;
+
+	mask1 = create_cpumask();
+	if (!mask1)
+		return 0;
+
+	mask2 = create_cpumask();
+	if (!mask2)
+		goto release_exit;
+
+	bpf_cpumask_set_cpu(0, mask1);
+	bpf_cpumask_set_cpu(1, mask2);
+
+	first = bpf_cpumask_first_and(cast(mask1), cast(mask2));
+	if (first <= 1)
+		err = 3;
+
+release_exit:
+	if (mask1)
+		bpf_cpumask_release(mask1);
+	if (mask2)
+		bpf_cpumask_release(mask2);
+	return 0;
+}
+
 SEC("tp_btf/task_newtask")
 int BPF_PROG(test_test_and_set_clear, struct task_struct *task, u64 clone_flags)
 {
-- 
2.40.1

Re: [PATCH bpf-next 2/5] selftests/bpf: Add test for new bpf_cpumask_first_and() kfunc

[Yonghong Song]

On 6/9/23 8:50 PM, David Vernet wrote:
> A prior patch added a new kfunc called bpf_cpumask_first_and() which
> wraps cpumask_first_and(). This patch adds a selftest to validate its
> behavior.
> 
> Signed-off-by: David Vernet <void@manifault.com>

Acked-by: Yonghong Song <yhs@fb.com>

[PATCH bpf-next 3/5] bpf: Replace bpf_cpumask_any* with bpf_cpumask_any_distribute*

[David Vernet]

We currently export the bpf_cpumask_any() and bpf_cpumask_any_and()
kfuncs. Intuitively, one would expect these to choose any CPU in the
cpumask, but what they actually do is alias to cpumask_first() and
cpmkas_first_and().

This is useless given that we already export bpf_cpumask_first() and
bpf_cpumask_first_and(), so this patch replaces them with kfuncs that
call cpumask_any_distribute() and cpumask_any_and_distribute(), which
actually choose any CPU from the cpumask (or the AND of two cpumasks for
the latter).

Signed-off-by: David Vernet <void@manifault.com>
---
 kernel/bpf/cpumask.c | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/kernel/bpf/cpumask.c b/kernel/bpf/cpumask.c
index 9416c8ac8a04..938a60ff4295 100644
--- a/kernel/bpf/cpumask.c
+++ b/kernel/bpf/cpumask.c
@@ -382,7 +382,7 @@ __bpf_kfunc void bpf_cpumask_copy(struct bpf_cpumask *dst, const struct cpumask
 }
 
 /**
- * bpf_cpumask_any() - Return a random set CPU from a cpumask.
+ * bpf_cpumask_any_distribute() - Return a random set CPU from a cpumask.
  * @cpumask: The cpumask being queried.
  *
  * Return:
@@ -391,26 +391,28 @@ __bpf_kfunc void bpf_cpumask_copy(struct bpf_cpumask *dst, const struct cpumask
  *
  * A struct bpf_cpumask pointer may be safely passed to @src.
  */
-__bpf_kfunc u32 bpf_cpumask_any(const struct cpumask *cpumask)
+__bpf_kfunc u32 bpf_cpumask_any_distribute(const struct cpumask *cpumask)
 {
-	return cpumask_any(cpumask);
+	return cpumask_any_distribute(cpumask);
 }
 
 /**
- * bpf_cpumask_any_and() - Return a random set CPU from the AND of two
- *			   cpumasks.
+ * bpf_cpumask_any_and_distribute() - Return a random set CPU from the AND of
+ *				      two cpumasks.
  * @src1: The first cpumask.
  * @src2: The second cpumask.
  *
  * Return:
- * * A random set bit within [0, num_cpus) if at least one bit is set.
+ * * A random set bit within [0, num_cpus) from the AND of two cpumasks, if at
+ *   least one bit is set.
  * * >= num_cpus if no bit is set.
  *
  * struct bpf_cpumask pointers may be safely passed to @src1 and @src2.
  */
-__bpf_kfunc u32 bpf_cpumask_any_and(const struct cpumask *src1, const struct cpumask *src2)
+__bpf_kfunc u32 bpf_cpumask_any_and_distribute(const struct cpumask *src1,
+					       const struct cpumask *src2)
 {
-	return cpumask_any_and(src1, src2);
+	return cpumask_any_and_distribute(src1, src2);
 }
 
 __diag_pop();
@@ -438,8 +440,8 @@ BTF_ID_FLAGS(func, bpf_cpumask_subset, KF_RCU)
 BTF_ID_FLAGS(func, bpf_cpumask_empty, KF_RCU)
 BTF_ID_FLAGS(func, bpf_cpumask_full, KF_RCU)
 BTF_ID_FLAGS(func, bpf_cpumask_copy, KF_RCU)
-BTF_ID_FLAGS(func, bpf_cpumask_any, KF_RCU)
-BTF_ID_FLAGS(func, bpf_cpumask_any_and, KF_RCU)
+BTF_ID_FLAGS(func, bpf_cpumask_any_distribute, KF_RCU)
+BTF_ID_FLAGS(func, bpf_cpumask_any_and_distribute, KF_RCU)
 BTF_SET8_END(cpumask_kfunc_btf_ids)
 
 static const struct btf_kfunc_id_set cpumask_kfunc_set = {
-- 
2.40.1

Re: [PATCH bpf-next 3/5] bpf: Replace bpf_cpumask_any* with bpf_cpumask_any_distribute*

[Yonghong Song]

On 6/9/23 8:50 PM, David Vernet wrote:
> We currently export the bpf_cpumask_any() and bpf_cpumask_any_and()
> kfuncs. Intuitively, one would expect these to choose any CPU in the
> cpumask, but what they actually do is alias to cpumask_first() and
> cpmkas_first_and().
> 
> This is useless given that we already export bpf_cpumask_first() and
> bpf_cpumask_first_and(), so this patch replaces them with kfuncs that
> call cpumask_any_distribute() and cpumask_any_and_distribute(), which
> actually choose any CPU from the cpumask (or the AND of two cpumasks for
> the latter).
> 
> Signed-off-by: David Vernet <void@manifault.com>

Acked-by: Yonghong Song <yhs@fb.com>

[PATCH bpf-next 4/5] selftests/bpf: Update bpf_cpumask_any* tests to use bpf_cpumask_any_distribute*

[David Vernet]

In a prior patch, we removed the bpf_cpumask_any() and
bpf_cpumask_any_and() kfuncs, and replaced them with
bpf_cpumask_any_distribute() and bpf_cpumask_any_distribute_and().
The advertised semantics between the two kfuncs were identical, with the
former always returning the first CPU, and the latter actually returning
any CPU.

This patch updates the selftests for these kfuncs to use the new names.

Signed-off-by: David Vernet <void@manifault.com>
---
 tools/testing/selftests/bpf/progs/cpumask_common.h  | 4 ++--
 tools/testing/selftests/bpf/progs/cpumask_success.c | 8 ++++----
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/tools/testing/selftests/bpf/progs/cpumask_common.h b/tools/testing/selftests/bpf/progs/cpumask_common.h
index b3493d5d263e..b15c588ace15 100644
--- a/tools/testing/selftests/bpf/progs/cpumask_common.h
+++ b/tools/testing/selftests/bpf/progs/cpumask_common.h
@@ -52,8 +52,8 @@ bool bpf_cpumask_subset(const struct cpumask *src1, const struct cpumask *src2)
 bool bpf_cpumask_empty(const struct cpumask *cpumask) __ksym;
 bool bpf_cpumask_full(const struct cpumask *cpumask) __ksym;
 void bpf_cpumask_copy(struct bpf_cpumask *dst, const struct cpumask *src) __ksym;
-u32 bpf_cpumask_any(const struct cpumask *src) __ksym;
-u32 bpf_cpumask_any_and(const struct cpumask *src1, const struct cpumask *src2) __ksym;
+u32 bpf_cpumask_any_distribute(const struct cpumask *src) __ksym;
+u32 bpf_cpumask_any_and_distribute(const struct cpumask *src1, const struct cpumask *src2) __ksym;
 
 void bpf_rcu_read_lock(void) __ksym;
 void bpf_rcu_read_unlock(void) __ksym;
diff --git a/tools/testing/selftests/bpf/progs/cpumask_success.c b/tools/testing/selftests/bpf/progs/cpumask_success.c
index fbaf510f4ab5..674a63424dee 100644
--- a/tools/testing/selftests/bpf/progs/cpumask_success.c
+++ b/tools/testing/selftests/bpf/progs/cpumask_success.c
@@ -344,13 +344,13 @@ int BPF_PROG(test_copy_any_anyand, struct task_struct *task, u64 clone_flags)
 	bpf_cpumask_set_cpu(1, mask2);
 	bpf_cpumask_or(dst1, cast(mask1), cast(mask2));
 
-	cpu = bpf_cpumask_any(cast(mask1));
+	cpu = bpf_cpumask_any_distribute(cast(mask1));
 	if (cpu != 0) {
 		err = 6;
 		goto release_exit;
 	}
 
-	cpu = bpf_cpumask_any(cast(dst2));
+	cpu = bpf_cpumask_any_distribute(cast(dst2));
 	if (cpu < nr_cpus) {
 		err = 7;
 		goto release_exit;
@@ -362,13 +362,13 @@ int BPF_PROG(test_copy_any_anyand, struct task_struct *task, u64 clone_flags)
 		goto release_exit;
 	}
 
-	cpu = bpf_cpumask_any(cast(dst2));
+	cpu = bpf_cpumask_any_distribute(cast(dst2));
 	if (cpu > 1) {
 		err = 9;
 		goto release_exit;
 	}
 
-	cpu = bpf_cpumask_any_and(cast(mask1), cast(mask2));
+	cpu = bpf_cpumask_any_and_distribute(cast(mask1), cast(mask2));
 	if (cpu < nr_cpus) {
 		err = 10;
 		goto release_exit;
-- 
2.40.1

Re: [PATCH bpf-next 4/5] selftests/bpf: Update bpf_cpumask_any* tests to use bpf_cpumask_any_distribute*

[Yonghong Song]

On 6/9/23 8:50 PM, David Vernet wrote:
> In a prior patch, we removed the bpf_cpumask_any() and
> bpf_cpumask_any_and() kfuncs, and replaced them with
> bpf_cpumask_any_distribute() and bpf_cpumask_any_distribute_and().
> The advertised semantics between the two kfuncs were identical, with the
> former always returning the first CPU, and the latter actually returning
> any CPU.
> 
> This patch updates the selftests for these kfuncs to use the new names.
> 
> Signed-off-by: David Vernet <void@manifault.com>

Acked-by: Yonghong Song <yhs@fb.com>

[PATCH bpf-next 5/5] bpf/docs: Update documentation for new cpumask kfuncs

[David Vernet]

We recently added the bpf_cpumask_first_and() kfunc, and changed
bpf_cpumask_any() / bpf_cpumask_any_and() to
bpf_cpumask_any_distribute() and bpf_cpumask_any_distribute_and()
respectively. This patch adds an entry for the bpf_cpumask_first_and()
kfunc, and updates the documentation for the *any* kfuncs to the new
names.

Signed-off-by: David Vernet <void@manifault.com>
---
 Documentation/bpf/cpumasks.rst | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/Documentation/bpf/cpumasks.rst b/Documentation/bpf/cpumasks.rst
index 41efd8874eeb..3139c7c02e79 100644
--- a/Documentation/bpf/cpumasks.rst
+++ b/Documentation/bpf/cpumasks.rst
@@ -351,14 +351,15 @@ In addition to the above kfuncs, there is also a set of read-only kfuncs that
 can be used to query the contents of cpumasks.
 
 .. kernel-doc:: kernel/bpf/cpumask.c
-   :identifiers: bpf_cpumask_first bpf_cpumask_first_zero bpf_cpumask_test_cpu
+   :identifiers: bpf_cpumask_first bpf_cpumask_first_zero bpf_cpumask_first_and
+                 bpf_cpumask_test_cpu
 
 .. kernel-doc:: kernel/bpf/cpumask.c
    :identifiers: bpf_cpumask_equal bpf_cpumask_intersects bpf_cpumask_subset
                  bpf_cpumask_empty bpf_cpumask_full
 
 .. kernel-doc:: kernel/bpf/cpumask.c
-   :identifiers: bpf_cpumask_any bpf_cpumask_any_and
+   :identifiers: bpf_cpumask_any_distribute bpf_cpumask_any_and_distribute
 
 ----
 
-- 
2.40.1

Re: [PATCH bpf-next 5/5] bpf/docs: Update documentation for new cpumask kfuncs

[Yonghong Song]

On 6/9/23 8:50 PM, David Vernet wrote:
> We recently added the bpf_cpumask_first_and() kfunc, and changed
> bpf_cpumask_any() / bpf_cpumask_any_and() to
> bpf_cpumask_any_distribute() and bpf_cpumask_any_distribute_and()
> respectively. This patch adds an entry for the bpf_cpumask_first_and()
> kfunc, and updates the documentation for the *any* kfuncs to the new
> names.
> 
> Signed-off-by: David Vernet <void@manifault.com>

Acked-by: Yonghong Song <yhs@fb.com>

Re: [PATCH bpf-next 1/5] bpf: Add bpf_cpumask_first_and() kfunc

[Yonghong Song]

On 6/9/23 8:50 PM, David Vernet wrote:
> We currently provide bpf_cpumask_first(), bpf_cpumask_any(), and
> bpf_cpumask_any_and() kfuncs. bpf_cpumask_any() and
> bpf_cpumask_any_and() are confusing misnomers in that they actually just
> call cpumask_first() and cpumask_first_and() respectively.
> 
> We'll replace them with bpf_cpumask_any_distribute() and
> bpf_cpumask_any_distribute_and() kfuncs in a subsequent patch, so let's
> ensure feature parity by adding a bpf_cpumask_first_and() kfunc to
> account for bpf_cpumask_any_and() being removed.
> 
> Signed-off-by: David Vernet <void@manifault.com>

Acked-by: Yonghong Song <yhs@fb.com>

Re: [PATCH bpf-next 1/5] bpf: Add bpf_cpumask_first_and() kfunc

[patchwork-bot+netdevbpf]

Hello:

This series was applied to bpf/bpf-next.git (master)
by Alexei Starovoitov <ast@kernel.org>:

On Fri,  9 Jun 2023 22:50:49 -0500 you wrote:
> We currently provide bpf_cpumask_first(), bpf_cpumask_any(), and
> bpf_cpumask_any_and() kfuncs. bpf_cpumask_any() and
> bpf_cpumask_any_and() are confusing misnomers in that they actually just
> call cpumask_first() and cpumask_first_and() respectively.
> 
> We'll replace them with bpf_cpumask_any_distribute() and
> bpf_cpumask_any_distribute_and() kfuncs in a subsequent patch, so let's
> ensure feature parity by adding a bpf_cpumask_first_and() kfunc to
> account for bpf_cpumask_any_and() being removed.
> 
> [...]

Here is the summary with links:
  - [bpf-next,1/5] bpf: Add bpf_cpumask_first_and() kfunc
    https://git.kernel.org/bpf/bpf-next/c/5ba3a7a851e3
  - [bpf-next,2/5] selftests/bpf: Add test for new bpf_cpumask_first_and() kfunc
    https://git.kernel.org/bpf/bpf-next/c/58476d8a24bd
  - [bpf-next,3/5] bpf: Replace bpf_cpumask_any* with bpf_cpumask_any_distribute*
    https://git.kernel.org/bpf/bpf-next/c/f983be917332
  - [bpf-next,4/5] selftests/bpf: Update bpf_cpumask_any* tests to use bpf_cpumask_any_distribute*
    https://git.kernel.org/bpf/bpf-next/c/5a73efc7d1b4
  - [bpf-next,5/5] bpf/docs: Update documentation for new cpumask kfuncs
    https://git.kernel.org/bpf/bpf-next/c/25085b4e9251

You are awesome, thank you!
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