lkml.org 
[lkml]   [1999]   [Dec]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    SubjectRe: deadlock avoidance?
    Date
    Wednesday, December 08, 1999 1:53 AM
    Johannes Erdfelt <jerdfelt@sventech.com> wrote :
    > > All pid and count modify fall inside 1) a nested lock ( ie. the task
    > > already own the lock : ++lock->count )
    > > 2) a lock acquired : lock->pid = getpid() and ++lock->count
    >
    > The setting is, but not all of the reading.
    >

    Hi Johannes,

    There is not test & set operations other than spin_... in my code.
    Look at it better and try to find a sequence of operations that stall it.


    struct s_nested_lock {
    spinlock_t lock;
    short int pid;
    short int count;
    };


    #define nested_lock(lock, flags) \
    if (lock->pid == getpid()) { \
    ++lock->count; \
    } else { \
    spin_lock_irqsave(&lock->lock, flags); \
    ++lock->count; \
    lock->pid = getpid(); \
    }

    #define nested_unlock(lock, flags) \
    if (--lock->count == 0) { \
    lock->pid = 0; \
    spin_unlock_irqrestore(&lock->lock, flags); \
    }


    Cheers,
    Davide.

    --
    "Debian, the Freedom in Freedom."



    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.rutgers.edu
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2005-03-22 13:55    [W:0.022 / U:3.340 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site