Re: [PATCH v2 4/5] uprobes: kill uprobe_register_refctr()

Masami Hiramatsu
2024-07-31T05:37:52Z

On Mon, 29 Jul 2024 15:45:30 +0200
Oleg Nesterov <oleg@redhat.com> wrote:

> It doesn't make any sense to have 2 versions of _register(). Note that
> trace_uprobe_enable(), the only user of uprobe_register(), doesn't need
> to check tu->ref_ctr_offset to decide which one should be used, it could
> safely pass ref_ctr_offset == 0 to uprobe_register_refctr().
>
> Add this argument to uprobe_register(), update the callers, and kill
> uprobe_register_refctr().
>
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>
> Acked-by: Andrii Nakryiko <andrii@kernel.org>
> ---
> include/linux/uprobes.h | 9 ++-------
> kernel/events/uprobes.c | 24 ++++++------------------
> kernel/trace/bpf_trace.c | 8 ++++----
> kernel/trace/trace_uprobe.c | 7 +------
> 4 files changed, 13 insertions(+), 35 deletions(-)

OK, but it seems

tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c

is still using uprobe_register_refctr().

That should be updated too.

Thanks,

>
> diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
> index b503fafb7fb3..440316fbf3c6 100644
> --- a/include/linux/uprobes.h
> +++ b/include/linux/uprobes.h
> @@ -110,8 +110,7 @@ extern bool is_trap_insn(uprobe_opcode_t *insn);
> extern unsigned long uprobe_get_swbp_addr(struct pt_regs *regs);
> extern unsigned long uprobe_get_trap_addr(struct pt_regs *regs);
> extern int uprobe_write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr, uprobe_opcode_t);
> -extern int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc);
> -extern int uprobe_register_refctr(struct inode *inode, loff_t offset, loff_t ref_ctr_offset, struct uprobe_consumer *uc);
> +extern int uprobe_register(struct inode *inode, loff_t offset, loff_t ref_ctr_offset, struct uprobe_consumer *uc);
> extern int uprobe_apply(struct inode *inode, loff_t offset, struct uprobe_consumer *uc, bool);
> extern void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc);
> extern int uprobe_mmap(struct vm_area_struct *vma);
> @@ -152,11 +151,7 @@ static inline void uprobes_init(void)
> #define uprobe_get_trap_addr(regs) instruction_pointer(regs)
>
> static inline int
> -uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc)
> -{
> - return -ENOSYS;
> -}
> -static inline int uprobe_register_refctr(struct inode *inode, loff_t offset, loff_t ref_ctr_offset, struct uprobe_consumer *uc)
> +uprobe_register(struct inode *inode, loff_t offset, loff_t ref_ctr_offset, struct uprobe_consumer *uc)
> {
> return -ENOSYS;
> }
> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
> index dfe6306a63b1..b7f40bad8abc 100644
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -1121,25 +1121,26 @@ void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consume
> EXPORT_SYMBOL_GPL(uprobe_unregister);
>
> /*
> - * __uprobe_register - register a probe
> + * uprobe_register - register a probe
> * @inode: the file in which the probe has to be placed.
> * @offset: offset from the start of the file.
> + * @ref_ctr_offset: offset of SDT marker / reference counter
> * @uc: information on howto handle the probe..
> *
> - * Apart from the access refcount, __uprobe_register() takes a creation
> + * Apart from the access refcount, uprobe_register() takes a creation
> * refcount (thro alloc_uprobe) if and only if this @uprobe is getting
> * inserted into the rbtree (i.e first consumer for a @inode:@offset
> * tuple). Creation refcount stops uprobe_unregister from freeing the
> * @uprobe even before the register operation is complete. Creation
> * refcount is released when the last @uc for the @uprobe
> - * unregisters. Caller of __uprobe_register() is required to keep @inode
> + * unregisters. Caller of uprobe_register() is required to keep @inode
> * (and the containing mount) referenced.
> *
> * Return errno if it cannot successully install probes
> * else return 0 (success)
> */
> -static int __uprobe_register(struct inode *inode, loff_t offset,
> - loff_t ref_ctr_offset, struct uprobe_consumer *uc)
> +int uprobe_register(struct inode *inode, loff_t offset, loff_t ref_ctr_offset,
> + struct uprobe_consumer *uc)
> {
> struct uprobe *uprobe;
> int ret;
> @@ -1189,21 +1190,8 @@ static int __uprobe_register(struct inode *inode, loff_t offset,
> goto retry;
> return ret;
> }
> -
> -int uprobe_register(struct inode *inode, loff_t offset,
> - struct uprobe_consumer *uc)
> -{
> - return __uprobe_register(inode, offset, 0, uc);
> -}
> EXPORT_SYMBOL_GPL(uprobe_register);
>
> -int uprobe_register_refctr(struct inode *inode, loff_t offset,
> - loff_t ref_ctr_offset, struct uprobe_consumer *uc)
> -{
> - return __uprobe_register(inode, offset, ref_ctr_offset, uc);
> -}
> -EXPORT_SYMBOL_GPL(uprobe_register_refctr);
> -
> /*
> * uprobe_apply - unregister an already registered probe.
> * @inode: the file in which the probe has to be removed.
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index cd098846e251..afa909e17824 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -3480,10 +3480,10 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
> &bpf_uprobe_multi_link_lops, prog);
>
> for (i = 0; i < cnt; i++) {
> - err = uprobe_register_refctr(d_real_inode(link->path.dentry),
> - uprobes[i].offset,
> - uprobes[i].ref_ctr_offset,
> - &uprobes[i].consumer);
> + err = uprobe_register(d_real_inode(link->path.dentry),
> + uprobes[i].offset,
> + uprobes[i].ref_ctr_offset,
> + &uprobes[i].consumer);
> if (err) {
> bpf_uprobe_unregister(&path, uprobes, i);
> goto error_free;
> diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
> index c98e3b3386ba..1f590f989c1e 100644
> --- a/kernel/trace/trace_uprobe.c
> +++ b/kernel/trace/trace_uprobe.c
> @@ -1089,12 +1089,7 @@ static int trace_uprobe_enable(struct trace_uprobe *tu, filter_func_t filter)
> tu->consumer.filter = filter;
> tu->inode = d_real_inode(tu->path.dentry);
>
> - if (tu->ref_ctr_offset)
> - ret = uprobe_register_refctr(tu->inode, tu->offset,
> - tu->ref_ctr_offset, &tu->consumer);
> - else
> - ret = uprobe_register(tu->inode, tu->offset, &tu->consumer);
> -
> + ret = uprobe_register(tu->inode, tu->offset, tu->ref_ctr_offset, &tu->consumer);
> if (ret)
> tu->inode = NULL;
>
> --
> 2.25.1.362.g51ebf55
>

--
Masami Hiramatsu (Google) <mhiramat@kernel.org>