linux-kernel - Re: [PATCH v2] hpet: Fix missing '=' character in the __setup() code of hpet_mmap

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Date:   Thu, 20 Dec 2018 13:29:32 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Buland Singh <bsingh@...hat.com>
Cc:     clemens@...isch.de, arnd@...db.de, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Subject: Re: [PATCH v2] hpet: Fix missing '=' character in the __setup() code
 of hpet_mmap_enable

On Thu, Dec 20, 2018 at 05:35:24PM +0530, Buland Singh wrote:
> Commit '3d035f580699 ("drivers/char/hpet.c: allow user controlled mmap for
> user processes")' introduced a new kernel command line parameter hpet_mmap,
> that is required to expose the memory map of the HPET registers to
> user-space. Unfortunately the kernel command line parameter 'hpet_mmap' is
> broken and never takes effect due to missing '=' character in the __setup()
> code of hpet_mmap_enable.
> 
> Before this patch:
> 
> dmesg output with the kernel command line parameter hpet_mmap=1
> 
> [    0.204152] HPET mmap disabled
> 
> dmesg output with the kernel command line parameter hpet_mmap=0
> 
> [    0.204192] HPET mmap disabled
> 
> After this patch:
> 
> dmesg output with the kernel command line parameter hpet_mmap=1
> 
> [    0.203945] HPET mmap enabled
> 
> dmesg output with the kernel command line parameter hpet_mmap=0
> 
> [    0.204652] HPET mmap disabled
> 
> Fixes: 3d035f580699 ("drivers/char/hpet.c: allow user controlled mmap for user processes")
> Signed-off-by: Buland Singh <bsingh@...hat.com>
> ---
>  drivers/char/hpet.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/char/hpet.c b/drivers/char/hpet.c
> index 4a22b4b41aef..9bffcd37cc7b 100644
> --- a/drivers/char/hpet.c
> +++ b/drivers/char/hpet.c
> @@ -377,7 +377,7 @@ static __init int hpet_mmap_enable(char *str)
>  	pr_info("HPET mmap %s\n", hpet_mmap_enabled ? "enabled" : "disabled");
>  	return 1;
>  }
> -__setup("hpet_mmap", hpet_mmap_enable);
> +__setup("hpet_mmap=", hpet_mmap_enable);

This has _never_ worked?  Since 3.13?  Why not just remove the thing as
it is obvious no one actually has ever used it.  That would make the
code even simpler :)

thanks,

greg k-h