Re: [PATCH] crypto: cavium/nitrox - Fix 'File exists' error in 'nitrox_probe()'

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Fri, Nov 12, 2021 at 12:54:00AM -0800, Aayush Agarwal wrote:
> When two cavium cards are inserted and on booting OS,
> nitrox_debugfs_init() is called twice and thus tries to create
> 'n5pf' directory twice inside '/'. This causes the 'File exists' error.
> 
> This error was handled before
> 'commit 97a93b2b5839 ("crypto: cavium/nitrox - no need to check return
> value of debugfs_create functions")'
> 
> This commit handles the error by redirecting the code by checking
> if 'n5pf' directory exists already using 'debugfs_lookup()' function.
> 
> Tested-by: Evan Xuan <jian.xuan@oracle.com>
> Signed-off-by: Aayush Agarwal <aayush.a.agarwal@oracle.com>
> ---
>  drivers/crypto/cavium/nitrox/nitrox_main.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/crypto/cavium/nitrox/nitrox_main.c b/drivers/crypto/cavium/nitrox/nitrox_main.c
> index 6c61817996a3..1eee05e30f05 100644
> --- a/drivers/crypto/cavium/nitrox/nitrox_main.c
> +++ b/drivers/crypto/cavium/nitrox/nitrox_main.c
> @@ -7,6 +7,7 @@
>  #include <linux/mutex.h>
>  #include <linux/pci.h>
>  #include <linux/pci_ids.h>
> +#include <linux/debugfs.h>
>  
>  #include "nitrox_dev.h"
>  #include "nitrox_common.h"
> @@ -479,6 +480,13 @@ static int nitrox_probe(struct pci_dev *pdev,
>  	if (err)
>  		goto pf_hw_fail;
>  
> +	struct dentry *check_dir = debugfs_lookup(KBUILD_MODNAME, NULL);
> +
> +	if (check_dir != NULL) {
> +		dput(check_dir);
> +		goto pf_hw_fail;

Why is this a "failure"?

> +	}
> +
>  	nitrox_debugfs_init(ndev);

Why not just put the "check" logic in this function instead?
You want to have per-device directories in debugfs for this device,
right?  If so, then this function should handle that, not the
nitrox_probe() call.

thanks,

greg k-h