Hi,
I should know the answer to this, but... When reading a global kernel
variable, where its modifications are protected by a mutex, is it
necessary to get the mutex lock to just read its value?
For example:
A if ((mp->mnt_kern_flag & MNTK_UNMOUNTF) != 0)
return (EPERM);
versus
B MNT_ILOCK(mp);
if ((mp->mnt_kern_flag & MNTK_UNMOUNTF) != 0) {
MNT_IUNLOCK(mp);
return (EPERM);
}
MNT_IUNLOCK(mp);
My hunch is that B is necessary if you need an up-to-date value
for the variable (mp->mnt_kern_flag in this case).
Is that correct?
Thanks in advance for help with this, rick
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