usb: dwc3: Fix dentry leak in dwc3_gadget_free_endpoints

From: Bruce Chen <bruce.chen@unisoc.com>

When using debugfs_remove_recursive leaks a dentry with
a hotplug stress test, the phone runs out of memory.

Thus fix the issue by using the newly created debugfs_lookup_and_remove().

Signed-off-by: Bruce Chen <bruce.chen@unisoc.com>
Signed-off-by: Cixi Geng <cixi.geng1@unisoc.com>
---
 drivers/usb/dwc3/core.h    | 1 +
 drivers/usb/dwc3/debugfs.c | 3 ++-
 drivers/usb/dwc3/gadget.c  | 4 +---
 3 files changed, 4 insertions(+), 4 deletions(-)

Greg KH <gregkh@linuxfoundation.org> 于2022年10月28日周五 17:13写道：
>
> On Fri, Oct 28, 2022 at 04:49:19PM +0800, Cixi Geng wrote:
> > From: Bruce Chen <bruce.chen@unisoc.com>
> >
> > When using debugfs_remove_recursive leaks a dentry with
> > a hotplug stress test, the phone runs out of memory.
> >
> > Thus fix the issue by using the newly created debugfs_lookup_and_remove().
> >
> > Signed-off-by: Bruce Chen <bruce.chen@unisoc.com>
> > Signed-off-by: Cixi Geng <cixi.geng1@unisoc.com>
> > ---
> >  drivers/usb/dwc3/core.h    | 1 +
> >  drivers/usb/dwc3/debugfs.c | 3 ++-
> >  drivers/usb/dwc3/gadget.c  | 4 +---
> >  3 files changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> > index 8f9959ba9fd4..ba3ecaa7f06c 100644
> > --- a/drivers/usb/dwc3/core.h
> > +++ b/drivers/usb/dwc3/core.h
> > @@ -1261,6 +1261,7 @@ struct dwc3 {
> >       u8                      num_eps;
> >
> >       struct dwc3_hwparams    hwparams;
> > +     struct dentry           *root;
>
> You forgot to document this new variable.
>
> And name it a bit better?
>
> >       struct debugfs_regset32 *regset;
> >
> >       u32                     dbg_lsp_select;
> > diff --git a/drivers/usb/dwc3/debugfs.c b/drivers/usb/dwc3/debugfs.c
> > index f2b7675c7f62..b9af4a81f51d 100644
> > --- a/drivers/usb/dwc3/debugfs.c
> > +++ b/drivers/usb/dwc3/debugfs.c
> > @@ -911,6 +911,7 @@ void dwc3_debugfs_init(struct dwc3 *dwc)
> >       dwc->regset->base = dwc->regs - DWC3_GLOBALS_REGS_START;
> >
> >       root = debugfs_create_dir(dev_name(dwc->dev), usb_debug_root);
> > +     dwc->root = root;
> >       debugfs_create_regset32("regdump", 0444, root, dwc->regset);
> >       debugfs_create_file("lsp_dump", 0644, root, dwc, &dwc3_lsp_fops);
> >
> > @@ -929,6 +930,6 @@ void dwc3_debugfs_init(struct dwc3 *dwc)
> >
> >  void dwc3_debugfs_exit(struct dwc3 *dwc)
> >  {
> > -     debugfs_remove(debugfs_lookup(dev_name(dwc->dev), usb_debug_root));
> > +     debugfs_remove(dwc->root);
> >       kfree(dwc->regset);
> >  }
> > diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> > index 079cd333632e..6d6c188fcbea 100644
> > --- a/drivers/usb/dwc3/gadget.c
> > +++ b/drivers/usb/dwc3/gadget.c
> > @@ -3172,9 +3172,7 @@ static void dwc3_gadget_free_endpoints(struct dwc3 *dwc)
> >                       list_del(&dep->endpoint.ep_list);
> >               }
> >
> > -             debugfs_remove_recursive(debugfs_lookup(dep->name,
> > -                             debugfs_lookup(dev_name(dep->dwc->dev),
> > -                                            usb_debug_root)));
> > +             debugfs_lookup_and_remove(dep->name, dwc->root);
> >               kfree(dep);
> >       }
> >  }
> > --
> > 2.34.1
> >
>
> I don't think this is the full fix.
>
> Below is a patch that I've had in a tree that I need to push out (along
> with the other 33 debugfs_lookup patches) that should resolve this for
> this driver in a more complete way.
>
> Can you try this version instead?
We test OK by using the following patch. thanks.

Best Regards
Cixi Geng
>
> thanks,
>
> greg k-h
>
> ---------------------
>
>
> From 49b893792579af1bea46c5004759cb35475c4fca Mon Sep 17 00:00:00 2001
> From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Date: Fri, 2 Sep 2022 16:41:39 +0200
> Subject: [PATCH 06/34] USB: dwc3: debugfs_lookup() fix
>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
>  drivers/usb/dwc3/core.h    |  2 ++
>  drivers/usb/dwc3/debug.h   |  3 +++
>  drivers/usb/dwc3/debugfs.c | 19 ++++++++-----------
>  drivers/usb/dwc3/gadget.c  |  4 +---
>  4 files changed, 14 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index 8f9959ba9fd4..582ebd9cf9c2 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -1117,6 +1117,7 @@ struct dwc3_scratchpad_array {
>   *                  address.
>   * @num_ep_resized: carries the current number endpoints which have had its tx
>   *                 fifo resized.
> + * @debug_root: root debugfs directory for this device to put its files in.
>   */
>  struct dwc3 {
>         struct work_struct      drd_work;
> @@ -1332,6 +1333,7 @@ struct dwc3 {
>         int                     max_cfg_eps;
>         int                     last_fifo_depth;
>         int                     num_ep_resized;
> +       struct dentry           *debug_root;
>  };
>
>  #define INCRX_BURST_MODE 0
> diff --git a/drivers/usb/dwc3/debug.h b/drivers/usb/dwc3/debug.h
> index 48b44b88dc25..8bb2c9e3b9ac 100644
> --- a/drivers/usb/dwc3/debug.h
> +++ b/drivers/usb/dwc3/debug.h
> @@ -414,11 +414,14 @@ static inline const char *dwc3_gadget_generic_cmd_status_string(int status)
>
>  #ifdef CONFIG_DEBUG_FS
>  extern void dwc3_debugfs_create_endpoint_dir(struct dwc3_ep *dep);
> +extern void dwc3_debugfs_remove_endpoint_dir(struct dwc3_ep *dep);
>  extern void dwc3_debugfs_init(struct dwc3 *d);
>  extern void dwc3_debugfs_exit(struct dwc3 *d);
>  #else
>  static inline void dwc3_debugfs_create_endpoint_dir(struct dwc3_ep *dep)
>  {  }
> +static inline void dwc3_debugfs_remove_endpoint_dir(struct dwc3_ep *dep)
> +{  }
>  static inline void dwc3_debugfs_init(struct dwc3 *d)
>  {  }
>  static inline void dwc3_debugfs_exit(struct dwc3 *d)
> diff --git a/drivers/usb/dwc3/debugfs.c b/drivers/usb/dwc3/debugfs.c
> index f2b7675c7f62..850df0e6bcab 100644
> --- a/drivers/usb/dwc3/debugfs.c
> +++ b/drivers/usb/dwc3/debugfs.c
> @@ -873,27 +873,23 @@ static const struct dwc3_ep_file_map dwc3_ep_file_map[] = {
>         { "GDBGEPINFO", &dwc3_ep_info_register_fops, },
>  };
>
> -static void dwc3_debugfs_create_endpoint_files(struct dwc3_ep *dep,
> -               struct dentry *parent)
> +void dwc3_debugfs_create_endpoint_dir(struct dwc3_ep *dep)
>  {
> +       struct dentry           *dir;
>         int                     i;
>
> +       dir = debugfs_create_dir(dep->name, dep->dwc->debug_root);
>         for (i = 0; i < ARRAY_SIZE(dwc3_ep_file_map); i++) {
>                 const struct file_operations *fops = dwc3_ep_file_map[i].fops;
>                 const char *name = dwc3_ep_file_map[i].name;
>
> -               debugfs_create_file(name, 0444, parent, dep, fops);
> +               debugfs_create_file(name, 0444, dir, dep, fops);
>         }
>  }
>
> -void dwc3_debugfs_create_endpoint_dir(struct dwc3_ep *dep)
> +void dwc3_debugfs_remove_endpoint_dir(struct dwc3_ep *dep)
>  {
> -       struct dentry           *dir;
> -       struct dentry           *root;
> -
> -       root = debugfs_lookup(dev_name(dep->dwc->dev), usb_debug_root);
> -       dir = debugfs_create_dir(dep->name, root);
> -       dwc3_debugfs_create_endpoint_files(dep, dir);
> +       debugfs_lookup_and_remove(dep->name, dep->dwc->debug_root);
>  }
>
>  void dwc3_debugfs_init(struct dwc3 *dwc)
> @@ -911,6 +907,7 @@ void dwc3_debugfs_init(struct dwc3 *dwc)
>         dwc->regset->base = dwc->regs - DWC3_GLOBALS_REGS_START;
>
>         root = debugfs_create_dir(dev_name(dwc->dev), usb_debug_root);
> +       dwc->debug_root = root;
>         debugfs_create_regset32("regdump", 0444, root, dwc->regset);
>         debugfs_create_file("lsp_dump", 0644, root, dwc, &dwc3_lsp_fops);
>
> @@ -929,6 +926,6 @@ void dwc3_debugfs_init(struct dwc3 *dwc)
>
>  void dwc3_debugfs_exit(struct dwc3 *dwc)
>  {
> -       debugfs_remove(debugfs_lookup(dev_name(dwc->dev), usb_debug_root));
> +       debugfs_lookup_and_remove(dev_name(dwc->dev), usb_debug_root);
>         kfree(dwc->regset);
>  }
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 079cd333632e..404bb7ee61a8 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -3172,9 +3172,7 @@ static void dwc3_gadget_free_endpoints(struct dwc3 *dwc)
>                         list_del(&dep->endpoint.ep_list);
>                 }
>
> -               debugfs_remove_recursive(debugfs_lookup(dep->name,
> -                               debugfs_lookup(dev_name(dep->dwc->dev),
> -                                              usb_debug_root)));
> +               dwc3_debugfs_remove_endpoint_dir(dep);
>                 kfree(dep);
>         }
>  }
> --
> 2.38.1
>