Regarding enumerating Block devices registered in kernel mode

Regarding enumerating Block devices registered in kernel mode

[vaibhav]

Hi Mentors,

 

I am working on a kernel module wherein I need to enumerate all the block
devices registered with the kernel. Also looking for notifications when a
block device gets added/remove. Google didn't help much and the thought of
reading the contents of /sys/block from kernel mode  looks messy to me.
Looking for guidance on performing this enumeration.

 

Thanks,

VJ

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Regarding enumerating Block devices registered in kernel mode

[Richard Weinberger]

On Tue, Nov 12, 2013 at 6:24 AM, vaibhav <vaibhav92@hotmail.com> wrote:
> I am working on a kernel module wherein I need to enumerate all the block
> devices registered with the kernel. Also looking for notifications when a
> block device gets added/remove. Google didn?t help much and the thought of
> reading the contents of /sys/block from kernel mode  looks messy to me.
> Looking for guidance on performing this enumeration.

Why do you need this within the kernel?
Sounds much like a userspace job done in kernel land...

-- 
Thanks,
//richard

Regarding enumerating Block devices registered in kernel mode

[vaibhav]

Thanks for replying Richard,

I need to access the blockdevice structure associated with each block device
so that I can patch its block_device_operations to receive ioctls calls in
my code. In my code I check for ioctls that I handle and pass it to the
original ioctl handler if the ioctl is not understood by me.  

I intend to patch these block_device structures during my module
initialization hence I need to iterate all BD's available in the system at
that point. Also need to keep track of new BD's appearing in the system so
that I can patch them as soon as they are available.

Thanks Again,
VJ

-----Original Message-----
From: Richard Weinberger [mailto:richard.weinberger at gmail.com] 
Sent: Tuesday, November 12, 2013 1:39 PM
To: vaibhav
Cc: kernelnewbies
Subject: Re: Regarding enumerating Block devices registered in kernel mode

On Tue, Nov 12, 2013 at 6:24 AM, vaibhav <vaibhav92@hotmail.com> wrote:
> I am working on a kernel module wherein I need to enumerate all the 
> block devices registered with the kernel. Also looking for 
> notifications when a block device gets added/remove. Google didn't 
> help much and the thought of reading the contents of /sys/block from
kernel mode  looks messy to me.
> Looking for guidance on performing this enumeration.

Why do you need this within the kernel?
Sounds much like a userspace job done in kernel land...

--
Thanks,
//richard

Regarding enumerating Block devices registered in kernel mode

[Richard Weinberger]

Am 12.11.2013 09:47, schrieb vaibhav:
> Thanks for replying Richard,
> 
> I need to access the blockdevice structure associated with each block device
> so that I can patch its block_device_operations to receive ioctls calls in
> my code. In my code I check for ioctls that I handle and pass it to the
> original ioctl handler if the ioctl is not understood by me.  
> 
> I intend to patch these block_device structures during my module
> initialization hence I need to iterate all BD's available in the system at
> that point. Also need to keep track of new BD's appearing in the system so
> that I can patch them as soon as they are available.

Please don't do that.
Such patching/hooking/etc...-games are doomed to failure.

Thanks,
//richard