kernel_optimize_test/include
Arnd Bergmann ef3fb2422f scsi: fc: use get/put_unaligned64 for wwn access
A bug in the gcc-6.0 prerelease version caused at least one
driver (lpfc) to have excessive stack usage when dealing with
wwn data, on the ARM architecture.

lpfc_scsi.c: In function 'lpfc_find_next_oas_lun':
lpfc_scsi.c:117:1: warning: the frame size of 1152 bytes is larger than 1024 bytes [-Wframe-larger-than=]

I have reported this as a gcc regression in
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70232

However, using a better implementation of wwn_to_u64() not only
helps with the particular gcc problem but also leads to better
object code for any version or architecture.

The kernel already provides get_unaligned_be64() and
put_unaligned_be64() helper functions that provide an
optimized implementation with the desired semantics.

The lpfc_find_next_oas_lun() function in the example that
grew from 1146 bytes to 5144 bytes when moving from gcc-5.3
to gcc-6.0 is now 804 bytes, as the optimized
get_unaligned_be64() load can be done in three instructions.
The stack usage is now down to 28 bytes from 128 bytes with
gcc-5.3 before.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Hannes Reinicke <hare@suse.de>
Reviewed-by: Ewan Milne <emilne@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2016-03-18 15:29:58 -04:00
..
acpi ACPI / CPPC: remove redundant mbox_send_message() declaration 2016-02-03 01:09:52 +01:00
asm-generic powerpc fixes for 4.5 #2 2016-02-20 09:22:11 -08:00
clocksource
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2016-01-22 11:58:43 -08:00
drm drm/atomic: Allow for holes in connector state, v2. 2016-02-19 13:24:03 +10:00
dt-bindings clk: tegra: Add the APB2APE audio clock on Tegra210 2016-02-02 15:49:29 +01:00
keys
kvm
linux NFS client bugfixes for Linux 4.5 2016-02-23 16:39:21 -08:00
math-emu
media [media] vb2: fix nasty vb2_thread regression 2016-02-04 09:13:46 -02:00
memory
misc
net tcp/dccp: fix another race at listener dismantle 2016-02-18 11:35:51 -05:00
pcmcia
ras
rdma IB/mlx4: Enable send of RoCE QP1 packets with IP/UDP headers 2016-01-19 15:35:01 -05:00
rxrpc
scsi scsi: fc: use get/put_unaligned64 for wwn access 2016-03-18 15:29:58 -04:00
soc ARM: SoC driver updates for v4.5 2016-01-20 18:42:30 -08:00
sound ALSA: rawmidi: Make snd_rawmidi_transmit() race-free 2016-02-03 14:51:28 +01:00
target target/transport: add flag to indicate CPU Affinity is observed 2016-02-10 23:08:55 -08:00
trace This includes three minor fixes, mostly due to cut-and-paste issues. 2016-01-28 17:00:50 -08:00
uapi Merge branch 'libnvdimm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm 2016-02-01 15:21:20 -08:00
video
xen Merge branch 'for-4.5/drivers' of git://git.kernel.dk/linux-block 2016-01-21 18:19:38 -08:00
Kbuild