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From: Greg KH <gregkh@linuxfoundation.org>
To: Prateek Sood <prsood@codeaurora.org>
Cc: rafael@kernel.org, sramana@codeaurora.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH V2] drivers: core: Remove glue dirs early only when refcount is 1
Date: Wed, 1 May 2019 08:53:13 +0200	[thread overview]
Message-ID: <20190501065313.GA30616@kroah.com> (raw)
In-Reply-To: <1556684567-26710-1-git-send-email-prsood@codeaurora.org>

On Wed, May 01, 2019 at 09:52:47AM +0530, Prateek Sood wrote:
> While loading firmware blobs parallely in different threads, it is possible
> to free sysfs node of glue_dirs in device_del() from a thread while another
> thread is trying to add subdir from device_add() in glue_dirs sysfs node.
> 
>     CPU1                                           CPU2
> fw_load_sysfs_fallback()
>   device_add()
>     get_device_parent()
>       class_dir_create_and_add()
>         kobject_add_internal()
>           create_dir() // glue_dir
> 
>                                            fw_load_sysfs_fallback()
>                                              device_add()
>                                                get_device_parent()
>                                                  kobject_get() //glue_dir
> 
>   device_del()
>     cleanup_glue_dir()
>       kobject_del()
> 
>                                                kobject_add()
>                                                  kobject_add_internal()
>                                                    create_dir() // in glue_dir
>                                                      kernfs_create_dir_ns()
> 
>        sysfs_remove_dir() //glue_dir->sd=NULL
>        sysfs_put() // free glue_dir->sd
> 
>                                                        kernfs_new_node()
>                                                          kernfs_get(glue_dir)
> 
> Fix this race by making sure that kernfs_node for glue_dir is released only
> when refcount for glue_dir kobj is 1.
> 
> Signed-off-by: Prateek Sood <prsood@codeaurora.org>
> ---
>  drivers/base/core.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)

What changed from v1?  That always has to go below the --- line.

v3 please.

  reply	other threads:[~2019-05-01  6:53 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-30 13:55 [PATCH] drivers: core: Remove glue dirs early only when refcount is 1 Prateek Sood
2019-05-01  4:22 ` [PATCH V2] " Prateek Sood
2019-05-01  6:53   ` Greg KH [this message]
2019-05-01 11:59     ` [PATCH v3] " Prateek Sood
2019-05-06  5:11       ` Prateek Sood
2019-05-06  6:21         ` Greg KH
2019-05-24 19:04       ` Greg KH

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