Reuse module_attach infrastructure to add a new bare tracepoint to check
we can attach to it as a raw tracepoint.
Signed-off-by: Qais Yousef <[email protected]>
---
.../bpf/bpf_testmod/bpf_testmod-events.h | 6 +++++
.../selftests/bpf/bpf_testmod/bpf_testmod.c | 21 ++++++++++++++-
.../selftests/bpf/bpf_testmod/bpf_testmod.h | 6 +++++
.../selftests/bpf/prog_tests/module_attach.c | 27 +++++++++++++++++++
.../selftests/bpf/progs/test_module_attach.c | 10 +++++++
5 files changed, 69 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h
index b83ea448bc79..89c6d58e5dd6 100644
--- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h
+++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h
@@ -28,6 +28,12 @@ TRACE_EVENT(bpf_testmod_test_read,
__entry->pid, __entry->comm, __entry->off, __entry->len)
);
+/* A bare tracepoint with no event associated with it */
+DECLARE_TRACE(bpf_testmod_test_write_bare,
+ TP_PROTO(struct task_struct *task, struct bpf_testmod_test_write_ctx *ctx),
+ TP_ARGS(task, ctx)
+);
+
#endif /* _BPF_TESTMOD_EVENTS_H */
#undef TRACE_INCLUDE_PATH
diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
index 2df19d73ca49..e900adad2276 100644
--- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
+++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
@@ -28,9 +28,28 @@ bpf_testmod_test_read(struct file *file, struct kobject *kobj,
EXPORT_SYMBOL(bpf_testmod_test_read);
ALLOW_ERROR_INJECTION(bpf_testmod_test_read, ERRNO);
+noinline ssize_t
+bpf_testmod_test_write(struct file *file, struct kobject *kobj,
+ struct bin_attribute *bin_attr,
+ char *buf, loff_t off, size_t len)
+{
+ struct bpf_testmod_test_write_ctx ctx = {
+ .buf = buf,
+ .off = off,
+ .len = len,
+ };
+
+ trace_bpf_testmod_test_write_bare(current, &ctx);
+
+ return -EIO; /* always fail */
+}
+EXPORT_SYMBOL(bpf_testmod_test_write);
+ALLOW_ERROR_INJECTION(bpf_testmod_test_write, ERRNO);
+
static struct bin_attribute bin_attr_bpf_testmod_file __ro_after_init = {
- .attr = { .name = "bpf_testmod", .mode = 0444, },
+ .attr = { .name = "bpf_testmod", .mode = 0666, },
.read = bpf_testmod_test_read,
+ .write = bpf_testmod_test_write,
};
static int bpf_testmod_init(void)
diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
index b81adfedb4f6..b3892dc40111 100644
--- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
+++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
@@ -11,4 +11,10 @@ struct bpf_testmod_test_read_ctx {
size_t len;
};
+struct bpf_testmod_test_write_ctx {
+ char *buf;
+ loff_t off;
+ size_t len;
+};
+
#endif /* _BPF_TESTMOD_H */
diff --git a/tools/testing/selftests/bpf/prog_tests/module_attach.c b/tools/testing/selftests/bpf/prog_tests/module_attach.c
index 50796b651f72..e4605c0b5af1 100644
--- a/tools/testing/selftests/bpf/prog_tests/module_attach.c
+++ b/tools/testing/selftests/bpf/prog_tests/module_attach.c
@@ -21,9 +21,34 @@ static int trigger_module_test_read(int read_sz)
return 0;
}
+static int trigger_module_test_write(int write_sz)
+{
+ int fd, err;
+ char *buf = malloc(write_sz);
+
+ if (!buf)
+ return -ENOMEM;
+
+ memset(buf, 'a', write_sz);
+ buf[write_sz-1] = '\0';
+
+ fd = open("/sys/kernel/bpf_testmod", O_WRONLY);
+ err = -errno;
+ if (CHECK(fd < 0, "testmod_file_open", "failed: %d\n", err))
+ goto out;
+
+ write(fd, buf, write_sz);
+ close(fd);
+out:
+ free(buf);
+
+ return 0;
+}
+
void test_module_attach(void)
{
const int READ_SZ = 456;
+ const int WRITE_SZ = 457;
struct test_module_attach* skel;
struct test_module_attach__bss *bss;
int err;
@@ -48,8 +73,10 @@ void test_module_attach(void)
/* trigger tracepoint */
ASSERT_OK(trigger_module_test_read(READ_SZ), "trigger_read");
+ ASSERT_OK(trigger_module_test_write(WRITE_SZ), "trigger_write");
ASSERT_EQ(bss->raw_tp_read_sz, READ_SZ, "raw_tp");
+ ASSERT_EQ(bss->raw_tp_bare_write_sz, WRITE_SZ, "raw_tp_bare");
ASSERT_EQ(bss->tp_btf_read_sz, READ_SZ, "tp_btf");
ASSERT_EQ(bss->fentry_read_sz, READ_SZ, "fentry");
ASSERT_EQ(bss->fentry_manual_read_sz, READ_SZ, "fentry_manual");
diff --git a/tools/testing/selftests/bpf/progs/test_module_attach.c b/tools/testing/selftests/bpf/progs/test_module_attach.c
index efd1e287ac17..bd37ceec5587 100644
--- a/tools/testing/selftests/bpf/progs/test_module_attach.c
+++ b/tools/testing/selftests/bpf/progs/test_module_attach.c
@@ -17,6 +17,16 @@ int BPF_PROG(handle_raw_tp,
return 0;
}
+__u32 raw_tp_bare_write_sz = 0;
+
+SEC("raw_tp/bpf_testmod_test_write_bare")
+int BPF_PROG(handle_raw_tp_bare,
+ struct task_struct *task, struct bpf_testmod_test_write_ctx *write_ctx)
+{
+ raw_tp_bare_write_sz = BPF_CORE_READ(write_ctx, len);
+ return 0;
+}
+
__u32 tp_btf_read_sz = 0;
SEC("tp_btf/bpf_testmod_test_read")
--
2.25.1
On 1/16/21 10:21 AM, Qais Yousef wrote:
> Reuse module_attach infrastructure to add a new bare tracepoint to check
> we can attach to it as a raw tracepoint.
>
> Signed-off-by: Qais Yousef <[email protected]>
> ---
> .../bpf/bpf_testmod/bpf_testmod-events.h | 6 +++++
> .../selftests/bpf/bpf_testmod/bpf_testmod.c | 21 ++++++++++++++-
> .../selftests/bpf/bpf_testmod/bpf_testmod.h | 6 +++++
> .../selftests/bpf/prog_tests/module_attach.c | 27 +++++++++++++++++++
> .../selftests/bpf/progs/test_module_attach.c | 10 +++++++
> 5 files changed, 69 insertions(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h
> index b83ea448bc79..89c6d58e5dd6 100644
> --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h
> +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h
> @@ -28,6 +28,12 @@ TRACE_EVENT(bpf_testmod_test_read,
> __entry->pid, __entry->comm, __entry->off, __entry->len)
> );
>
> +/* A bare tracepoint with no event associated with it */
> +DECLARE_TRACE(bpf_testmod_test_write_bare,
> + TP_PROTO(struct task_struct *task, struct bpf_testmod_test_write_ctx *ctx),
> + TP_ARGS(task, ctx)
> +);
> +
> #endif /* _BPF_TESTMOD_EVENTS_H */
>
> #undef TRACE_INCLUDE_PATH
> diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
> index 2df19d73ca49..e900adad2276 100644
> --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
> +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
> @@ -28,9 +28,28 @@ bpf_testmod_test_read(struct file *file, struct kobject *kobj,
> EXPORT_SYMBOL(bpf_testmod_test_read);
> ALLOW_ERROR_INJECTION(bpf_testmod_test_read, ERRNO);
>
> +noinline ssize_t
> +bpf_testmod_test_write(struct file *file, struct kobject *kobj,
> + struct bin_attribute *bin_attr,
> + char *buf, loff_t off, size_t len)
> +{
> + struct bpf_testmod_test_write_ctx ctx = {
> + .buf = buf,
> + .off = off,
> + .len = len,
> + };
> +
> + trace_bpf_testmod_test_write_bare(current, &ctx);
> +
> + return -EIO; /* always fail */
> +}
> +EXPORT_SYMBOL(bpf_testmod_test_write);
> +ALLOW_ERROR_INJECTION(bpf_testmod_test_write, ERRNO);
> +
> static struct bin_attribute bin_attr_bpf_testmod_file __ro_after_init = {
Do we need to remove __ro_after_init?
> - .attr = { .name = "bpf_testmod", .mode = 0444, },
> + .attr = { .name = "bpf_testmod", .mode = 0666, },
> .read = bpf_testmod_test_read,
> + .write = bpf_testmod_test_write,
> };
>
> static int bpf_testmod_init(void)
> diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
> index b81adfedb4f6..b3892dc40111 100644
> --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
> +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
> @@ -11,4 +11,10 @@ struct bpf_testmod_test_read_ctx {
> size_t len;
> };
>
> +struct bpf_testmod_test_write_ctx {
> + char *buf;
> + loff_t off;
> + size_t len;
> +};
> +
> #endif /* _BPF_TESTMOD_H */
> diff --git a/tools/testing/selftests/bpf/prog_tests/module_attach.c b/tools/testing/selftests/bpf/prog_tests/module_attach.c
> index 50796b651f72..e4605c0b5af1 100644
> --- a/tools/testing/selftests/bpf/prog_tests/module_attach.c
> +++ b/tools/testing/selftests/bpf/prog_tests/module_attach.c
> @@ -21,9 +21,34 @@ static int trigger_module_test_read(int read_sz)
> return 0;
> }
>
> +static int trigger_module_test_write(int write_sz)
> +{
> + int fd, err;
Init err = 0?
> + char *buf = malloc(write_sz);
> +
> + if (!buf)
> + return -ENOMEM;
Looks like we already non-negative value, so return ENOMEM?
> +
> + memset(buf, 'a', write_sz);
> + buf[write_sz-1] = '\0';
> +
> + fd = open("/sys/kernel/bpf_testmod", O_WRONLY);
> + err = -errno;
> + if (CHECK(fd < 0, "testmod_file_open", "failed: %d\n", err))
> + goto out;
Change the above to
fd = open("/sys/kernel/bpf_testmod", O_WRONLY);
if (CHECK(fd < 0, "testmod_file_open", "failed: %d\n", errno)) {
err = -errno;
goto out;
}
> +
> + write(fd, buf, write_sz);
> + close(fd);
> +out:
> + free(buf);
> +
No need for extra line here.
> + return 0;
return err.
> +}
> +
> void test_module_attach(void)
> {
> const int READ_SZ = 456;
> + const int WRITE_SZ = 457;
> struct test_module_attach* skel;
> struct test_module_attach__bss *bss;
> int err;
> @@ -48,8 +73,10 @@ void test_module_attach(void)
>
> /* trigger tracepoint */
> ASSERT_OK(trigger_module_test_read(READ_SZ), "trigger_read");
> + ASSERT_OK(trigger_module_test_write(WRITE_SZ), "trigger_write");
>
> ASSERT_EQ(bss->raw_tp_read_sz, READ_SZ, "raw_tp");
> + ASSERT_EQ(bss->raw_tp_bare_write_sz, WRITE_SZ, "raw_tp_bare");
> ASSERT_EQ(bss->tp_btf_read_sz, READ_SZ, "tp_btf");
> ASSERT_EQ(bss->fentry_read_sz, READ_SZ, "fentry");
> ASSERT_EQ(bss->fentry_manual_read_sz, READ_SZ, "fentry_manual");
> diff --git a/tools/testing/selftests/bpf/progs/test_module_attach.c b/tools/testing/selftests/bpf/progs/test_module_attach.c
> index efd1e287ac17..bd37ceec5587 100644
> --- a/tools/testing/selftests/bpf/progs/test_module_attach.c
> +++ b/tools/testing/selftests/bpf/progs/test_module_attach.c
> @@ -17,6 +17,16 @@ int BPF_PROG(handle_raw_tp,
> return 0;
> }
>
> +__u32 raw_tp_bare_write_sz = 0;
> +
> +SEC("raw_tp/bpf_testmod_test_write_bare")
> +int BPF_PROG(handle_raw_tp_bare,
> + struct task_struct *task, struct bpf_testmod_test_write_ctx *write_ctx)
> +{
> + raw_tp_bare_write_sz = BPF_CORE_READ(write_ctx, len);
> + return 0;
> +}
> +
> __u32 tp_btf_read_sz = 0;
>
> SEC("tp_btf/bpf_testmod_test_read")
>
On 01/16/21 18:11, Yonghong Song wrote:
>
>
> On 1/16/21 10:21 AM, Qais Yousef wrote:
> > Reuse module_attach infrastructure to add a new bare tracepoint to check
> > we can attach to it as a raw tracepoint.
> >
> > Signed-off-by: Qais Yousef <[email protected]>
> > ---
> > .../bpf/bpf_testmod/bpf_testmod-events.h | 6 +++++
> > .../selftests/bpf/bpf_testmod/bpf_testmod.c | 21 ++++++++++++++-
> > .../selftests/bpf/bpf_testmod/bpf_testmod.h | 6 +++++
> > .../selftests/bpf/prog_tests/module_attach.c | 27 +++++++++++++++++++
> > .../selftests/bpf/progs/test_module_attach.c | 10 +++++++
> > 5 files changed, 69 insertions(+), 1 deletion(-)
> >
> > diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h
> > index b83ea448bc79..89c6d58e5dd6 100644
> > --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h
> > +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h
> > @@ -28,6 +28,12 @@ TRACE_EVENT(bpf_testmod_test_read,
> > __entry->pid, __entry->comm, __entry->off, __entry->len)
> > );
> > +/* A bare tracepoint with no event associated with it */
> > +DECLARE_TRACE(bpf_testmod_test_write_bare,
> > + TP_PROTO(struct task_struct *task, struct bpf_testmod_test_write_ctx *ctx),
> > + TP_ARGS(task, ctx)
> > +);
> > +
> > #endif /* _BPF_TESTMOD_EVENTS_H */
> > #undef TRACE_INCLUDE_PATH
> > diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
> > index 2df19d73ca49..e900adad2276 100644
> > --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
> > +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
> > @@ -28,9 +28,28 @@ bpf_testmod_test_read(struct file *file, struct kobject *kobj,
> > EXPORT_SYMBOL(bpf_testmod_test_read);
> > ALLOW_ERROR_INJECTION(bpf_testmod_test_read, ERRNO);
> > +noinline ssize_t
> > +bpf_testmod_test_write(struct file *file, struct kobject *kobj,
> > + struct bin_attribute *bin_attr,
> > + char *buf, loff_t off, size_t len)
> > +{
> > + struct bpf_testmod_test_write_ctx ctx = {
> > + .buf = buf,
> > + .off = off,
> > + .len = len,
> > + };
> > +
> > + trace_bpf_testmod_test_write_bare(current, &ctx);
> > +
> > + return -EIO; /* always fail */
> > +}
> > +EXPORT_SYMBOL(bpf_testmod_test_write);
> > +ALLOW_ERROR_INJECTION(bpf_testmod_test_write, ERRNO);
> > +
> > static struct bin_attribute bin_attr_bpf_testmod_file __ro_after_init = {
>
> Do we need to remove __ro_after_init?
I don't think so. The structure should still remain RO AFAIU.
>
> > - .attr = { .name = "bpf_testmod", .mode = 0444, },
> > + .attr = { .name = "bpf_testmod", .mode = 0666, },
> > .read = bpf_testmod_test_read,
> > + .write = bpf_testmod_test_write,
> > };
> > static int bpf_testmod_init(void)
> > diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
> > index b81adfedb4f6..b3892dc40111 100644
> > --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
> > +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
> > @@ -11,4 +11,10 @@ struct bpf_testmod_test_read_ctx {
> > size_t len;
> > };
> > +struct bpf_testmod_test_write_ctx {
> > + char *buf;
> > + loff_t off;
> > + size_t len;
> > +};
> > +
> > #endif /* _BPF_TESTMOD_H */
> > diff --git a/tools/testing/selftests/bpf/prog_tests/module_attach.c b/tools/testing/selftests/bpf/prog_tests/module_attach.c
> > index 50796b651f72..e4605c0b5af1 100644
> > --- a/tools/testing/selftests/bpf/prog_tests/module_attach.c
> > +++ b/tools/testing/selftests/bpf/prog_tests/module_attach.c
> > @@ -21,9 +21,34 @@ static int trigger_module_test_read(int read_sz)
> > return 0;
> > }
> > +static int trigger_module_test_write(int write_sz)
> > +{
> > + int fd, err;
>
> Init err = 0?
I don't see what difference this makes.
>
> > + char *buf = malloc(write_sz);
> > +
> > + if (!buf)
> > + return -ENOMEM;
>
> Looks like we already non-negative value, so return ENOMEM?
We already set err=-errno. So shouldn't we return negative too?
>
> > +
> > + memset(buf, 'a', write_sz);
> > + buf[write_sz-1] = '\0';
> > +
> > + fd = open("/sys/kernel/bpf_testmod", O_WRONLY);
> > + err = -errno;
> > + if (CHECK(fd < 0, "testmod_file_open", "failed: %d\n", err))
> > + goto out;
>
> Change the above to
> fd = open("/sys/kernel/bpf_testmod", O_WRONLY);
> if (CHECK(fd < 0, "testmod_file_open", "failed: %d\n", errno)) {
> err = -errno;
> goto out;
> }
I kept the code consistent with the definition of trigger_module_test_read().
I'll leave it up to the maintainer to pick up the style changes if they prefer
it this way.
Thanks for the ack and for the review.
Cheers
--
Qais Yousef
On 1/18/21 4:18 AM, Qais Yousef wrote:
> On 01/16/21 18:11, Yonghong Song wrote:
>>
>>
>> On 1/16/21 10:21 AM, Qais Yousef wrote:
>>> Reuse module_attach infrastructure to add a new bare tracepoint to check
>>> we can attach to it as a raw tracepoint.
>>>
>>> Signed-off-by: Qais Yousef <[email protected]>
>>> ---
>>> .../bpf/bpf_testmod/bpf_testmod-events.h | 6 +++++
>>> .../selftests/bpf/bpf_testmod/bpf_testmod.c | 21 ++++++++++++++-
>>> .../selftests/bpf/bpf_testmod/bpf_testmod.h | 6 +++++
>>> .../selftests/bpf/prog_tests/module_attach.c | 27 +++++++++++++++++++
>>> .../selftests/bpf/progs/test_module_attach.c | 10 +++++++
>>> 5 files changed, 69 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h
>>> index b83ea448bc79..89c6d58e5dd6 100644
>>> --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h
>>> +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h
>>> @@ -28,6 +28,12 @@ TRACE_EVENT(bpf_testmod_test_read,
>>> __entry->pid, __entry->comm, __entry->off, __entry->len)
>>> );
>>> +/* A bare tracepoint with no event associated with it */
>>> +DECLARE_TRACE(bpf_testmod_test_write_bare,
>>> + TP_PROTO(struct task_struct *task, struct bpf_testmod_test_write_ctx *ctx),
>>> + TP_ARGS(task, ctx)
>>> +);
>>> +
>>> #endif /* _BPF_TESTMOD_EVENTS_H */
>>> #undef TRACE_INCLUDE_PATH
>>> diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
>>> index 2df19d73ca49..e900adad2276 100644
>>> --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
>>> +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
>>> @@ -28,9 +28,28 @@ bpf_testmod_test_read(struct file *file, struct kobject *kobj,
>>> EXPORT_SYMBOL(bpf_testmod_test_read);
>>> ALLOW_ERROR_INJECTION(bpf_testmod_test_read, ERRNO);
>>> +noinline ssize_t
>>> +bpf_testmod_test_write(struct file *file, struct kobject *kobj,
>>> + struct bin_attribute *bin_attr,
>>> + char *buf, loff_t off, size_t len)
>>> +{
>>> + struct bpf_testmod_test_write_ctx ctx = {
>>> + .buf = buf,
>>> + .off = off,
>>> + .len = len,
>>> + };
>>> +
>>> + trace_bpf_testmod_test_write_bare(current, &ctx);
>>> +
>>> + return -EIO; /* always fail */
>>> +}
>>> +EXPORT_SYMBOL(bpf_testmod_test_write);
>>> +ALLOW_ERROR_INJECTION(bpf_testmod_test_write, ERRNO);
>>> +
>>> static struct bin_attribute bin_attr_bpf_testmod_file __ro_after_init = {
>>
>> Do we need to remove __ro_after_init?
>
> I don't think so. The structure should still remain RO AFAIU.
okay.
>
>>
>>> - .attr = { .name = "bpf_testmod", .mode = 0444, },
>>> + .attr = { .name = "bpf_testmod", .mode = 0666, },
>>> .read = bpf_testmod_test_read,
>>> + .write = bpf_testmod_test_write,
>>> };
>>> static int bpf_testmod_init(void)
>>> diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
>>> index b81adfedb4f6..b3892dc40111 100644
>>> --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
>>> +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
>>> @@ -11,4 +11,10 @@ struct bpf_testmod_test_read_ctx {
>>> size_t len;
>>> };
>>> +struct bpf_testmod_test_write_ctx {
>>> + char *buf;
>>> + loff_t off;
>>> + size_t len;
>>> +};
>>> +
>>> #endif /* _BPF_TESTMOD_H */
>>> diff --git a/tools/testing/selftests/bpf/prog_tests/module_attach.c b/tools/testing/selftests/bpf/prog_tests/module_attach.c
>>> index 50796b651f72..e4605c0b5af1 100644
>>> --- a/tools/testing/selftests/bpf/prog_tests/module_attach.c
>>> +++ b/tools/testing/selftests/bpf/prog_tests/module_attach.c
>>> @@ -21,9 +21,34 @@ static int trigger_module_test_read(int read_sz)
>>> return 0;
>>> }
>>> +static int trigger_module_test_write(int write_sz)
>>> +{
>>> + int fd, err;
>>
>> Init err = 0?
>
> I don't see what difference this makes.
>
>>
>>> + char *buf = malloc(write_sz);
>>> +
>>> + if (!buf)
>>> + return -ENOMEM;
>>
>> Looks like we already non-negative value, so return ENOMEM?
>
> We already set err=-errno. So shouldn't we return negative too?
Oh, yes, return -ENOMEM sounds right here.
>
>>
>>> +
>>> + memset(buf, 'a', write_sz);
>>> + buf[write_sz-1] = '\0';
>>> +
>>> + fd = open("/sys/kernel/bpf_testmod", O_WRONLY);
>>> + err = -errno;
>>> + if (CHECK(fd < 0, "testmod_file_open", "failed: %d\n", err))
>>> + goto out;
>>
>> Change the above to
>> fd = open("/sys/kernel/bpf_testmod", O_WRONLY);
>> if (CHECK(fd < 0, "testmod_file_open", "failed: %d\n", errno)) {
Here it should be ... "failed: %d\n", -errno.
>> err = -errno;
>> goto out;
>> }
>
> I kept the code consistent with the definition of trigger_module_test_read().
The original patch code:
+static int trigger_module_test_write(int write_sz)
+{
+ int fd, err;
+ char *buf = malloc(write_sz);
+
+ if (!buf)
+ return -ENOMEM;
+
+ memset(buf, 'a', write_sz);
+ buf[write_sz-1] = '\0';
+
+ fd = open("/sys/kernel/bpf_testmod", O_WRONLY);
+ err = -errno;
+ if (CHECK(fd < 0, "testmod_file_open", "failed: %d\n", err))
+ goto out;
+
+ write(fd, buf, write_sz);
+ close(fd);
+out:
+ free(buf);
+
+ return 0;
+}
Even for "fd < 0" case, it "goto out" and "return 0". We should return
error code here instead of 0.
Second, "err = -errno" is set before checking fd < 0. If fd >= 0, err
might inherit an postive errno from previous failure.
In trigger_module_test_write(), it is okay since the err is only used
when fd < 0:
err = -errno;
if (CHECK(fd < 0, "testmod_file_open", "failed: %d\n", err))
return err;
My above rewrite intends to use "err" during final "return" statement,
so I put assignment of "err = -errno" inside the CHECK branch.
But there are different ways to implement this properly.
>
> I'll leave it up to the maintainer to pick up the style changes if they prefer
> it this way.
>
> Thanks for the ack and for the review.
No problem.
>
> Cheers
>
> --
> Qais Yousef
>
Hi Yonghong
On 01/18/21 09:48, Yonghong Song wrote:
> The original patch code:
>
> +static int trigger_module_test_write(int write_sz)
> +{
> + int fd, err;
> + char *buf = malloc(write_sz);
> +
> + if (!buf)
> + return -ENOMEM;
> +
> + memset(buf, 'a', write_sz);
> + buf[write_sz-1] = '\0';
> +
> + fd = open("/sys/kernel/bpf_testmod", O_WRONLY);
> + err = -errno;
> + if (CHECK(fd < 0, "testmod_file_open", "failed: %d\n", err))
> + goto out;
> +
> + write(fd, buf, write_sz);
> + close(fd);
> +out:
> + free(buf);
> +
> + return 0;
> +}
>
> Even for "fd < 0" case, it "goto out" and "return 0". We should return
> error code here instead of 0.
>
> Second, "err = -errno" is set before checking fd < 0. If fd >= 0, err might
> inherit an postive errno from previous failure.
> In trigger_module_test_write(), it is okay since the err is only used
> when fd < 0:
> err = -errno;
> if (CHECK(fd < 0, "testmod_file_open", "failed: %d\n", err))
> return err;
>
> My above rewrite intends to use "err" during final "return" statement,
> so I put assignment of "err = -errno" inside the CHECK branch.
> But there are different ways to implement this properly.
Okay I see now. Sorry I missed your point initially. I will fix and send v3.
Thanks
--
Qais Yousef