Commit dfe2a77fd2 ("kfifo: fix kfifo_alloc() and kfifo_init()") made
the kfifo code round the number of elements up. That was good for
__kfifo_alloc(), but it's actually wrong for __kfifo_init().
The difference? __kfifo_alloc() will allocate the rounded-up number of
elements, but __kfifo_init() uses an allocation done by the caller. We
can't just say "use more elements than the caller allocated", and have
to round down.
The good news? All the normal cases will be using power-of-two arrays
anyway, and most users of kfifo's don't use kfifo_init() at all, but one
of the helper macros to declare a KFIFO that enforce the proper
power-of-two behavior. But it looks like at least ibmvscsis might be
affected.
The bad news? Will Deacon refers to an old thread and points points out
that the memory ordering in kfifo's is questionable. See
https://lore.kernel.org/lkml/20181211034032.32338-1-yuleixzhang@tencent.com/
for more.
Fixes: dfe2a77fd2 ("kfifo: fix kfifo_alloc() and kfifo_init()")
Reported-by: laokz <laokz@foxmail.com>
Cc: Stefani Seibold <stefani@seibold.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Greg KH <greg@kroah.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version this program is distributed in the
hope that it will be useful but without any warranty without even
the implied warranty of merchantability or fitness for a particular
purpose see the gnu general public license for more details you
should have received a copy of the gnu general public license along
with this program if not write to the free software foundation inc
675 mass ave cambridge ma 02139 usa
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-or-later
has been chosen to replace the boilerplate/reference in 441 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190520071858.739733335@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The comment in __kfifo_alloc says we round down, but we actually round
up, so correct it.
Signed-off-by: Martin Kelly <mkelly@xevo.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Use BUG_ON(x) rather than if(x) BUG();
The semantic patch that fixes this problem is as follows:
// <smpl>
@@ identifier x; @@
-if (!x) BUG();
+BUG_ON(!x);
// </smpl>
Signed-off-by: Himangi Saraogi <himangi774@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Cc: Stefani Seibold <stefani@seibold.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
'copied' and 'len' are in bytes, while 'ret' is in elements, so we need to
multiply 'ret' with the size of one element to get the correct result.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Cc: Stefani Seibold <stefani@seibold.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix kfifo_alloc() and kfifo_init() to alloc at least the requested number
of elements. Since the kfifo operates on power of 2 the request size will
be rounded up to the next power of two.
Signed-off-by: Stefani Seibold <stefani@seibold.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
