Ulrich Drepper <[EMAIL PROTECTED]> wrote: > In sys_faccessat you temporarily allocate a cred object which is > discarded in the end. With a few more macro definitions you could > create a dup_cred variant which initialized an automatic variable of > type struct cred. This way the kmalloc/kfree pair would fall away.
No, you can't. The filesystems sys_faccessat() then invokes are entitled to take a reference to it - the SunRPC authentication stuff, for example - so you can't just preemptively unallocate it as would occur with an automatic variable. > access is actually used frequently. For instance, ld.so uses it on > every startup as a quicker possibility to check for a file which > usually doesn't exist. So, speeding up access has some small effect > on performance. The resulting code might actually reduce the kernel > size a bit due to all the checks and calls which go away. A better way would be to compare fsuid/fsgid to uid/gid and to just take an extra ref on the incumbent cred object if they're the same, rather than always allocating a new one. That, I suspect, would speed up 99.99% of the cases. David - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
