lkml.org 
[lkml]   [2006]   [Sep]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectHow is Code in do_sys_settimeofday() safe in case of SMP and Nest Kernel Path?
    Hi, all,

    I got a question, that is, I am confused by the following code in
    do_sys_settimeofday().

    if (tz) {
    /* SMP safe, global irq locking makes it work. */
    sys_tz = *tz;
    if (firsttime) {
    firsttime = 0;
    if (!tv)
    warp_clock();
    }
    }


    For my understanding, an assignment between structs should be a
    bit-wise copy. Such operation is not atomic, so it can not be supposed
    SMP-safe. And the subsequent test-and-assign operation on firsttime is
    not atomic, either.

    If the comments mean the subsequent code is SMP-safe and can prevent
    nest-kernel-path, how does it achieves that?

    Thank you in advance.
    Feng,Dong
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2006-09-29 16:37    [W:0.026 / U:0.012 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site