lkml.org 
[lkml]   [2009]   [Nov]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH] misc: use a proper range for minor number dynamic allocation
    On Fri, 23 Oct 2009 21:28:17 -0200
    Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com> wrote:

    > The current dynamic allocation of minor number for misc devices has some
    > drawbacks.
    >
    > First of all, the range for dynamic numbers include some statically
    > allocated numbers. It goes from 63 to 0, and we have numbers in the
    > range from 1 to 15 already allocated. Although, it gives priority to the
    > higher and not allocated numbers, we may end up in a situation where we
    > must reject registering a driver which got a static number because a
    > driver got its number with dynamic allocation. Considering fs/dlm/user.c
    > allocates as many misc devices as lockspaces are created, and that we
    > have more than 50 users around, it's not unreasonable to reach that
    > situation.

    What is this DLM behaviour of which you speak? It sounds broken.

    > The proposed solution uses the not yet reserved range from 64 to 127. If
    > more devices are needed, we may push 64 to 16. Moreover, if we don't
    > need to give priority to the higher numbers anymore, we can start using
    > the bitmap/bitops functions.

    So... misc minors 64 to 127 are presently unused?

    > Finally, if there's a failure creating the device (because there's
    > already one with the same name, for example), the current implementation
    > does not clear the bit for the allocated minor and that number is lost
    > for future allocations.
    >

    Is that a bugfix for the existing code?

    If so, please split that out into a separate patch which we can review
    and apply promptly while we consider the broader problem which you've
    identified.




    \
     
     \ /
      Last update: 2009-11-09 22:31    [W:0.022 / U:59.544 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site