lkml.org 
[lkml]   [2015]   [Nov]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] mtd: phram: error handling
Hi Saurabh,

On Wed, Nov 11, 2015 at 01:53:58PM +0530, Saurabh Sengar wrote:
> Brian Norris wrote:
> > Well, today you're in luck! You're touching a driver that requires no
> > special hardware, so you should be able to test it.
>
> > I think you can try using the mem= kernel parameter (see
> > Documentation/kernel-parameters.txt) to restrict your system memory, and
> > then try using that unreachable portions of memory for phram. You can
> > try this driver as either a module or built-in. For the former, you can
> > specify the parameters during modprobe time, or later by writing to
> > /sys/module/phram/parameters/phram. For the latter, you can specify on
> > the kernel command line or in /sys/module/phram/parameters/phram.
>
> > Let me know if you have any more questions about testing your patch.
>
>
> Hi Brian,
>
> As you have suggested I have restricted my laptop's memory to 1GB and tried to access unreachable portion of memory(2GB).
> It seems to be successfully registered(this is OK right ?).

Seems OK.

> I have also tested below error scenarios; all exiting gracefully
> - parameter too long
> - too many arguments
> - not enough arguments
> - invalid start adddress
> - invalid device length

Nice! Glad to see you've tested quite a few good scenarios.

> This is my first interaction with phram device so I request you to verify my testing.
> Below are the commands and output I did for this testing.
>
> -----------------------------------------------------
> <restricting memory of my machine to 1 GB>
> saurabh@saurabh:~/little/Task02/linux$ cat /proc/meminfo | grep Mem
> MemTotal: 1016588 kB
> MemFree: 126016 kB
> MemAvailable: 295508 kB
> saurabh@saurabh:~/little/Task02/linux$ cat /proc/cmdline
> BOOT_IMAGE=/boot/vmlinuz-4.3.0-10333-gdfe4330-dirty mem=1024M root=UUID=2b66d4b2-ac21-4554-bf3b-64bc973e1dad ro quiet splash vt.handoff=7
>
> <accessing unreachable portions of memory>
> saurabh@saurabh:~/little/Task02/linux$ sudo insmod drivers/mtd/devices/phram.ko phram=ram,2048Mi,1ki
> saurabh@saurabh:~/little/Task02/linux$ sudo dmesg -c
> [ 634.748495] phram: ram device: 0x400 at 0x80000000
>
> <parameter too long>
> saurabh@saurabh:~/little/Task02/linux$ sudo insmod drivers/mtd/devices/phram.ko phram=abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz,256Mi,1Mi
> insmod: ERROR: could not insert module drivers/mtd/devices/phram.ko: Invalid parameters
> saurabh@saurabh:~/little/Task02/linux$ sudo dmesg -c
> [ 1469.763787] phram: parameter too long
> [ 1469.763797] phram: `abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz,256Mi,1Mi' invalid for parameter `phram'
>
>
> <too many arguments>
> saurabh@saurabh:~/little/Task02/linux$ sudo insmod drivers/mtd/devices/phram.ko phram=swap,256Mi,1Mi,extra_parameter
> insmod: ERROR: could not insert module drivers/mtd/devices/phram.ko: Invalid parameters
> saurabh@saurabh:~/little/Task02/linux$ sudo dmesg -c
> [ 1650.081694] phram: too many arguments
> [ 1650.081703] phram: `swap,256Mi,1Mi,extra_parameter' invalid for parameter `phram'
>
> <not enough arguments>
> saurabh@saurabh:~/little/Task02/linux$ sudo insmod drivers/mtd/devices/phram.ko phram=swap,256Mi
> insmod: ERROR: could not insert module drivers/mtd/devices/phram.ko: Invalid parameters
> saurabh@saurabh:~/little/Task02/linux$ sudo dmesg -c
> [ 1707.437130] phram: not enough arguments
> [ 1707.437138] phram: `swap,256Mi' invalid for parameter `phram'
>
>
> <invalid start address>
> saurabh@saurabh:~/little/Task02/linux$ sudo insmod drivers/mtd/devices/phram.ko phram=swap,256xyz,1Mi
> insmod: ERROR: could not insert module drivers/mtd/devices/phram.ko: Invalid parameters
> saurabh@saurabh:~/little/Task02/linux$ sudo dmesg -c
> [ 1783.014351] phram: invalid start address
> [ 1783.014359] phram: `swap,256xyz,1Mi' invalid for parameter `phram'
>
> <invalid device length>
> saurabh@saurabh:~/little/Task02/linux$ sudo insmod drivers/mtd/devices/phram.ko phram=swap,256Mi,1xyz
> insmod: ERROR: could not insert module drivers/mtd/devices/phram.ko: Invalid parameters
> saurabh@saurabh:~/little/Task02/linux$ sudo dmesg -c
> [ 1831.746108] phram: invalid device length
> [ 1831.746117] phram: `swap,256Mi,1xyz' invalid for parameter `phram'
> -------------------------------------------

This all looks very good. For the successful cases, it might be nice to
make sure you can still read and write the "device". (Try dd on
/dev/mtd0, or see mtd-utils for tools like flash_erase.) But you're not
touching the actual I/O behavior, so this isn't so important.

More importantly, it's good to test these cases too:

* phram is built-in (not a module), with and without a phram= line on
the commandline
* writing to /sys/module/phram/parameters/phram (for both the module
and built-in cases)

Thanks,
Brian


\
 
 \ /
  Last update: 2015-11-11 21:01    [W:0.083 / U:0.176 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site