linux/net
Linus Torvalds e1cff7002b bluetooth: don't use bitmaps for random flag accesses
The bluetooth code uses our bitmap infrastructure for the two bits (!)
of connection setup flags, and in the process causes odd problems when
it converts between a bitmap and just the regular values of said bits.

It's completely pointless to do things like bitmap_to_arr32() to convert
a bitmap into a u32.  It shoudln't have been a bitmap in the first
place.  The reason to use bitmaps is if you have arbitrary number of
bits you want to manage (not two!), or if you rely on the atomicity
guarantees of the bitmap setting and clearing.

The code could use an "atomic_t" and use "atomic_or/andnot()" to set and
clear the bit values, but considering that it then copies the bitmaps
around with "bitmap_to_arr32()" and friends, there clearly cannot be a
lot of atomicity requirements.

So just use a regular integer.

In the process, this avoids the warnings about erroneous use of
bitmap_from_u64() which were triggered on 32-bit architectures when
conversion from a u64 would access two words (and, surprise, surprise,
only one word is needed - and indeed overkill - for a 2-bit bitmap).

That was always problematic, but the compiler seems to notice it and
warn about the invalid pattern only after commit 0a97953fd2 ("lib: add
bitmap_{from,to}_arr64") changed the exact implementation details of
'bitmap_from_u64()', as reported by Sudip Mukherjee and Stephen Rothwell.

Fixes: fe92ee6425 ("Bluetooth: hci_core: Rework hci_conn_params flags")
Link: https://lore.kernel.org/all/YpyJ9qTNHJzz0FHY@debian/
Link: https://lore.kernel.org/all/20220606080631.0c3014f2@canb.auug.org.au/
Link: https://lore.kernel.org/all/20220605162537.1604762-1-yury.norov@gmail.com/
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reported-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Reviewed-by: Yury Norov <yury.norov@gmail.com>
Cc: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Cc: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-06-05 16:28:41 -07:00
..
6lowpan
9p
802
8021q
appletalk
atm
ax25
batman-adv
bluetooth
bpf
bpfilter
bridge
caif
can
ceph
core
dcb
dccp
decnet
dns_resolver
dsa
ethernet
ethtool
hsr
ieee802154
ife
ipv4
ipv6
iucv
kcm
key
l2tp
l3mdev
lapb
llc
mac80211
mac802154
mctp
mpls
mptcp
ncsi
netfilter
netlabel
netlink
netrom
nfc
nsh
openvswitch
packet
phonet
psample
qrtr
rds
rfkill
rose
rxrpc
sched
sctp
smc
strparser
sunrpc
switchdev
tipc
tls
unix
vmw_vsock
wireless
x25
xdp
xfrm
Kconfig
Kconfig.debug
Makefile
compat.c
devres.c
socket.c
sysctl_net.c