On 04/20/2015 10:46 PM, Jann Horn wrote: > The same thing was fixed for execve() in commit > 8b01fc86b9f425899f8a3a8fc1c47d73c2c20543, but for performance > reasons, that simple patch won't work for stat(). Thanks, Jann! Applied. Cheers, Michael > --- > man2/stat.2 | 23 +++++++++++++++++++++++ > 1 file changed, 23 insertions(+) > > diff --git a/man2/stat.2 b/man2/stat.2 > index 0d244af..69ec6a4 100644 > --- a/man2/stat.2 > +++ b/man2/stat.2 > @@ -175,6 +175,29 @@ that may be present between some fields on various architectures. > Consult the glibc and kernel source code > if you need to know the details. > > +\# Background: inode attributes are modified with i_mutex held, but > +\# read by stat() without taking the mutex. > +.I Note: > +For performance and simplicity reasons, different fields in the > +.I stat > +structure may contain state information from different moments > +during the execution of the syscall. For example, if > +.IR st_mode , > +.IR st_uid > +and > +.IR st_gid > +are changed by another process by calling > +.BR chown (2) , > +.BR stat () > +might return the old > +.I st_mode > +together with the new > +.IR st_uid , > +or the old > +.I st_uid > +together with the new > +.IR st_mode . > + > The > .I st_dev > field describes the device on which this file resides. > -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
