__diag_ignore_all("-Wmissing-prototypes",
"Global kfuncs as their definitions will be in BTF");
- struct task_struct *bpf_find_get_task_by_vpid(pid_t nr)
+ __bpf_kfunc struct task_struct *bpf_find_get_task_by_vpid(pid_t nr)
{
return find_get_task_by_vpid(nr);
}
This annotation is used to indicate a memory and size pair in the argument list.
An example is given below::
- void bpf_memzero(void *mem, int mem__sz)
+ __bpf_kfunc void bpf_memzero(void *mem, int mem__sz)
{
...
}
An example is given below::
- void *bpf_obj_new(u32 local_type_id__k, ...)
+ __bpf_kfunc void *bpf_obj_new(u32 local_type_id__k, ...)
{
...
}
This set encodes the BTF ID of each kfunc listed above, and encodes the flags
along with it. Ofcourse, it is also allowed to specify no flags.
+kfunc definitions should also always be annotated with the ``__bpf_kfunc``
+macro. This prevents issues such as the compiler inlining the kfunc if it's a
+static kernel function, or the function being elided in an LTO build as it's
+not used in the rest of the kernel. Developers should not manually add
+annotations to their kfunc to prevent these issues. If an annotation is
+required to prevent such an issue with your kfunc, it is a bug and should be
+added to the definition of the macro so that other kfuncs are similarly
+protected. An example is given below::
+
+ __bpf_kfunc struct task_struct *bpf_get_task_pid(s32 pid)
+ {
+ ...
+ }
+
2.4.1 KF_ACQUIRE flag
---------------------