Re: [PATCH v8 1/6] Uprobes: Simplify uprobe_register() body

[Song Liu <liu.song.a23@gmail.com>]

On Wed, Aug 8, 2018 at 9:18 PM, Ravi Bangoria
<ravi.bangoria@linux.ibm.com> wrote:
> Simplify uprobe_register() function body and let __uprobe_register()
> handle everything. Also move dependency functions around to fix build
> failures.
>
> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>

Reviewed-by: Song Liu <songliubraving@fb.com>

> ---
>  kernel/events/uprobes.c | 69 ++++++++++++++++++++++++++-----------------------
>  1 file changed, 36 insertions(+), 33 deletions(-)
>
> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
> index ccc579a7d32e..471eac896635 100644
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -840,13 +840,8 @@ register_for_each_vma(struct uprobe *uprobe, struct uprobe_consumer *new)
>         return err;
>  }
>
> -static int __uprobe_register(struct uprobe *uprobe, struct uprobe_consumer *uc)
> -{
> -       consumer_add(uprobe, uc);
> -       return register_for_each_vma(uprobe, uc);
> -}
> -
> -static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc)
> +static void
> +__uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc)
>  {
>         int err;
>
> @@ -860,24 +855,46 @@ static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *u
>  }
>
>  /*
> - * uprobe_register - register a probe
> + * uprobe_unregister - unregister a already registered probe.
> + * @inode: the file in which the probe has to be removed.
> + * @offset: offset from the start of the file.
> + * @uc: identify which probe if multiple probes are colocated.
> + */
> +void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc)
> +{
> +       struct uprobe *uprobe;
> +
> +       uprobe = find_uprobe(inode, offset);
> +       if (WARN_ON(!uprobe))
> +               return;
> +
> +       down_write(&uprobe->register_rwsem);
> +       __uprobe_unregister(uprobe, uc);
> +       up_write(&uprobe->register_rwsem);
> +       put_uprobe(uprobe);
> +}
> +EXPORT_SYMBOL_GPL(uprobe_unregister);
> +
> +/*
> + * __uprobe_register - register a probe
>   * @inode: the file in which the probe has to be placed.
>   * @offset: offset from the start of the file.
>   * @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)
>   */
> -int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc)
> +static int __uprobe_register(struct inode *inode, loff_t offset,
> +                            struct uprobe_consumer *uc)
>  {
>         struct uprobe *uprobe;
>         int ret;
> @@ -904,7 +921,8 @@ int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *
>         down_write(&uprobe->register_rwsem);
>         ret = -EAGAIN;
>         if (likely(uprobe_is_active(uprobe))) {
> -               ret = __uprobe_register(uprobe, uc);
> +               consumer_add(uprobe, uc);
> +               ret = register_for_each_vma(uprobe, uc);
>                 if (ret)
>                         __uprobe_unregister(uprobe, uc);
>         }
> @@ -915,6 +933,12 @@ int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *
>                 goto retry;
>         return ret;
>  }
> +
> +int uprobe_register(struct inode *inode, loff_t offset,
> +                   struct uprobe_consumer *uc)
> +{
> +       return __uprobe_register(inode, offset, uc);
> +}
>  EXPORT_SYMBOL_GPL(uprobe_register);
>
>  /*
> @@ -946,27 +970,6 @@ int uprobe_apply(struct inode *inode, loff_t offset,
>         return ret;
>  }
>
> -/*
> - * uprobe_unregister - unregister a already registered probe.
> - * @inode: the file in which the probe has to be removed.
> - * @offset: offset from the start of the file.
> - * @uc: identify which probe if multiple probes are colocated.
> - */
> -void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc)
> -{
> -       struct uprobe *uprobe;
> -
> -       uprobe = find_uprobe(inode, offset);
> -       if (WARN_ON(!uprobe))
> -               return;
> -
> -       down_write(&uprobe->register_rwsem);
> -       __uprobe_unregister(uprobe, uc);
> -       up_write(&uprobe->register_rwsem);
> -       put_uprobe(uprobe);
> -}
> -EXPORT_SYMBOL_GPL(uprobe_unregister);
> -
>  static int unapply_uprobe(struct uprobe *uprobe, struct mm_struct *mm)
>  {
>         struct vm_area_struct *vma;
> --
> 2.14.4
>