Hannes Frederic Sowa
a48e42920f
net: introduce new macro net_get_random_once ...
net_get_random_once is a new macro which handles the initialization
of secret keys. It is possible to call it in the fast path. Only the
initialization depends on the spinlock and is rather slow. Otherwise
it should get used just before the key is used to delay the entropy
extration as late as possible to get better randomness. It returns true
if the key got initialized.
The usage of static_keys for net_get_random_once is a bit uncommon so
it needs some further explanation why this actually works:
=== In the simple non-HAVE_JUMP_LABEL case we actually have ===
no constrains to use static_key_(true|false) on keys initialized with
STATIC_KEY_INIT_(FALSE|TRUE). So this path just expands in favor of
the likely case that the initialization is already done. The key is
initialized like this:
___done_key = { .enabled = ATOMIC_INIT(0) }
The check
if (!static_key_true(&___done_key)) \
expands into (pseudo code)
if (!likely(___done_key > 0))
, so we take the fast path as soon as ___done_key is increased from the
helper function.
=== If HAVE_JUMP_LABELs are available this depends ===
on patching of jumps into the prepared NOPs, which is done in
jump_label_init at boot-up time (from start_kernel). It is forbidden
and dangerous to use net_get_random_once in functions which are called
before that!
At compilation time NOPs are generated at the call sites of
net_get_random_once. E.g. net/ipv6/inet6_hashtable.c:inet6_ehashfn (we
need to call net_get_random_once two times in inet6_ehashfn, so two NOPs):
71: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
76: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
Both will be patched to the actual jumps to the end of the function to
call __net_get_random_once at boot time as explained above.
arch_static_branch is optimized and inlined for false as return value and
actually also returns false in case the NOP is placed in the instruction
stream. So in the fast case we get a "return false". But because we
initialize ___done_key with (enabled != (entries & 1)) this call-site
will get patched up at boot thus returning true. The final check looks
like this:
if (!static_key_true(&___done_key)) \
___ret = __net_get_random_once(buf, \
expands to
if (!!static_key_false(&___done_key)) \
___ret = __net_get_random_once(buf, \
So we get true at boot time and as soon as static_key_slow_inc is called
on the key it will invert the logic and return false for the fast path.
static_key_slow_inc will change the branch because it got initialized
with .enabled == 0. After static_key_slow_inc is called on the key the
branch is replaced with a nop again.
=== Misc: ===
The helper defers the increment into a workqueue so we don't
have problems calling this code from atomic sections. A seperate boolean
(___done) guards the case where we enter net_get_random_once again before
the increment happend.
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Eric Dumazet <edumazet@google.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-10-19 19:45:35 -04:00
dmaengine: PL08x: Add support for PL080S variant
2013-09-02 11:49:56 +05:30
bcma: make bcma_core_pci_{up,down}() callable from atomic context
2013-09-26 14:02:33 -04:00
can: mcp251x: Eliminate irq_flags from driver platform_data
2013-08-21 09:28:29 +02:00
libceph: add function to ensure notifies are complete
2013-09-09 11:15:49 -07:00
fsl /bestcomm
ARM: SoC cleanups for 3.12
2013-09-06 13:21:16 -07:00
ARM: SoC late changes for v3.12
2013-09-09 16:35:29 -07:00
MMC highlights for 3.12:
2013-09-10 13:33:09 -07:00
net/mlx4: Fix typo, move similar defs to same location
2013-10-17 15:10:50 -04:00
mmc: sdhci: get voltage from sdhc host
2013-08-26 11:32:07 -04:00
mtd: add a new ecc_step_size field to mtd_info{}
2013-08-30 21:37:01 +01:00
netfilter: nfnetlink: add batch support and use it from nf_tables
2013-10-14 18:01:01 +02:00
pinctrl: Pass all configs to driver on pin_config_set()
2013-08-28 13:34:41 +02:00
Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/cooloney/linux-leds
2013-09-12 11:35:33 -07:00
power: Add twl4030_madc battery driver.
2013-08-30 17:34:52 -07:00
md update for v3.12
2013-09-10 13:03:41 -07:00
regulator: fix fatal kernel-doc error
2013-09-17 11:49:25 +01:00
MMC highlights for 3.12:
2013-09-10 13:33:09 -07:00
ssb: provide phy address for Gigabit Ethernet driver
2013-10-02 15:40:57 -04:00
Merge branch 'nfsd-next' of git://linux-nfs.org/~bfields/linux
2013-09-10 20:04:59 -07:00
USBNET: fix handling padding packet
2013-09-28 15:42:49 -04:00
libata: Add support for SEND/RECEIVE FPDMA QUEUED
2013-08-25 09:39:12 -04:00
mm/page-writeback.c: add strictlimit feature
2013-09-11 15:58:04 -07:00
mm: avoid reinserting isolated balloon pages into LRU lists
2013-09-30 14:31:02 -07:00
exec: kill "int depth" in search_binary_handler()
2013-09-11 15:59:04 -07:00
block: Add nr_bios to block_rq_remap tracepoint
2013-09-21 13:57:47 -06:00
direct-io: Implement generic deferred AIO completions
2013-09-04 09:23:46 -04:00
userns: Kill nsown_capable it makes the wrong thing easy
2013-08-30 23:44:11 -07:00
cgroup: implement CFTYPE_NO_PREFIX
2013-08-26 18:40:56 -04:00
clk: wrap I/O access for improved portability
2013-08-27 17:50:38 -07:00
block: support embedded device command line partition
2013-09-11 15:56:57 -07:00
syscalls.h: add forward declarations for inplace syscall wrappers
2013-09-11 15:58:25 -07:00
Merge branch 'pm-cpufreq'
2013-08-27 01:44:40 +02:00
Remove GENERIC_HARDIRQ config option
2013-09-13 15:09:52 +02:00
Revert "cpufreq: make sure frequency transitions are serialized"
2013-09-10 02:54:50 +02:00
vmcore: introduce remap_oldmem_pfn_range()
2013-09-11 15:59:10 -07:00
Reinstate "crypto: crct10dif - Wrap crc_t10dif function all to use crypto transform framework"
2013-09-07 12:56:26 +10:00
super: fix calculation of shrinkable objects for small numbers
2013-09-10 18:56:29 -04:00
debugfs: provide debugfs_create_x64() when disabled
2013-08-27 22:09:12 -07:00
dm mpath: disable WRITE SAME if it fails
2013-09-20 10:36:34 -04:00
Merge branch 'for-v3.12' of git://git.linaro.org/people/mszyprowski/linux-dma-mapping
2013-09-09 10:26:33 -07:00
drivers: dma-contiguous: clean source code and prepare for device tree
2013-08-27 09:18:29 +02:00
drivers:net: Convert dma_alloc_coherent(...__GFP_ZERO) to dma_zalloc_coherent
2013-08-29 21:55:23 -04:00
Merge branch 'for-linus' of git://git.infradead.org/users/vkoul/slave-dma
2013-09-10 13:37:36 -07:00
[networking]device.h: Remove extern from function prototypes
2013-09-26 15:06:58 -07:00
Kill indirect include of file.h from eventfd.h, use fdget() in cgroup.c
2013-09-07 19:54:57 -04:00
f2fs: support the inline xattrs
2013-08-26 20:15:23 +09:00
[networking]device.h: Remove extern from function prototypes
2013-09-26 15:06:58 -07:00
[networking]device.h: Remove extern from function prototypes
2013-09-26 15:06:58 -07:00
net: fix unsafe set_memory_rw from softirq
2013-10-07 15:16:45 -04:00
a trivial writeback fix
2013-09-13 23:06:40 -04:00
fs_enet: cleanup clock API use
2013-08-22 22:13:54 -07:00
vfs: move get_fs_root_and_pwd() to single caller
2013-09-12 10:12:47 -07:00
FS-Cache: Add interface to check consistency of a cached object
2013-09-06 09:17:30 +01:00
fscache: Netfs function for cleanup post readpages
2013-09-06 09:17:30 +01:00
Merge branch 'rcu/next' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu
2013-09-03 07:41:11 +02:00
lib/genalloc.c: fix overflow of ending address of memory chunk
2013-09-11 15:57:35 -07:00
Remove GENERIC_HARDIRQ config option
2013-09-13 15:09:52 +02:00
video/hdmi: Rename HDMI_IDENTIFIER to HDMI_IEEE_OUI
2013-08-30 08:42:01 +10:00
HID: hid-sensor-hub: fix style of comments
2013-08-26 13:46:11 +02:00
HID: hid-sensor-hub: fix style of comments
2013-08-26 13:46:11 +02:00
HID: provide a helper for validating hid reports
2013-09-13 15:11:21 +02:00
HID: hidraw: Add spinlock in struct hidraw to protect list
2013-08-26 21:40:24 +02:00
[networking]device.h: Remove extern from function prototypes
2013-09-26 15:06:58 -07:00
thp: consolidate code between handle_mm_fault() and do_huge_pmd_anonymous_page()
2013-09-12 15:38:03 -07:00
mm: migrate: check movability of hugepage in unmap_and_move_huge_page()
2013-09-11 15:57:49 -07:00
Drivers: hv: util: Correctly support ws2008R2 and earlier
2013-09-26 14:20:21 -07:00
i2c: move ACPI helpers into the core
2013-08-23 10:22:29 +02:00
Input: add driver for slidebar on Lenovo IdeaPad laptops
2013-08-26 09:30:03 -07:00
ieee80211: fix vht cap definitions
2013-10-01 12:17:08 +02:00
[networking]device.h: Remove extern from function prototypes
2013-09-26 15:06:58 -07:00
initmpfs: move rootfs code from fs/ramfs/ to init/
2013-09-11 15:59:37 -07:00
Remove GENERIC_HARDIRQ config option
2013-09-13 15:09:52 +02:00
ipc: rename ids->rw_mutex
2013-09-11 15:59:42 -07:00
inet: includes a sock_common in request_sock
2013-10-10 00:08:07 -04:00
Remove GENERIC_HARDIRQ config option
2013-09-13 15:09:52 +02:00
Remove GENERIC_HARDIRQ config option
2013-09-13 15:09:52 +02:00
Remove GENERIC_HARDIRQ config option
2013-09-13 15:09:52 +02:00
jiffies: Avoid undefined behavior from signed overflow
2013-08-20 11:46:54 -07:00
static_key: WARN on usage before jump_label_init was called
2013-10-19 19:45:35 -04:00
static_key: WARN on usage before jump_label_init was called
2013-10-19 19:45:35 -04:00
lib: introduce upper case hex ascii helpers
2013-09-20 15:38:26 -04:00
Remove GENERIC_HARDIRQ config option
2013-09-13 15:09:52 +02:00
sysfs: Restrict mounting sysfs
2013-08-28 21:35:14 -07:00
kprobes: allow to specify custom allocator for insn caches
2013-09-11 15:58:52 -07:00
KVM: mmu: allow page tables to be in read-only slots
2013-09-17 12:52:31 +03:00
libata: Add support for queued DSM TRIM
2013-08-25 09:39:12 -04:00
list_lru: dynamically adjust node arrays
2013-09-10 18:56:32 -04:00
lockref: add ability to mark lockrefs "dead"
2013-09-07 15:49:18 -07:00
lz4: fix compression/decompression signedness mismatch
2013-09-11 15:59:45 -07:00
math64: New separate div64_u64_rem helper
2013-08-23 09:02:14 -04:00
memblock, numa: binary search node id
2013-09-11 15:57:51 -07:00
revert "memcg, vmscan: integrate soft reclaim tighter with zone shrinking code"
2013-09-24 17:00:26 -07:00
drivers: base: use standard device online/offline for state change
2013-08-21 11:52:20 -07:00
mm: migrate: remove VM_HUGETLB from vma flag check in vma_migratable()
2013-09-11 15:57:48 -07:00
phy: micrel: Add definitions for common Micrel PHY registers
2013-08-22 23:20:54 +08:00
Merge git://git.kvack.org/~bcrl/aio-next
2013-09-13 10:55:58 -07:00
thp: consolidate code between handle_mm_fault() and do_huge_pmd_anonymous_page()
2013-09-12 15:38:03 -07:00
mm: vmscan: fix do_try_to_free_pages() livelock
2013-09-11 15:58:01 -07:00
Merge git://git.kvack.org/~bcrl/aio-next
2013-09-13 10:55:58 -07:00
mm: vmscan: fix do_try_to_free_pages() livelock
2013-09-11 15:58:01 -07:00
Revert "Input: introduce BTN/ABS bits for drums and guitars"
2013-09-07 09:48:41 -07:00
module: Fix mod->mkobj.kobj potentially freed too early
2013-09-03 16:35:47 +09:30
module: Add flag to allow mod params to have no arguments
2013-08-20 15:37:42 +09:30
mutex: replace CONFIG_HAVE_ARCH_MUTEX_CPU_RELAX with simple ifdef
2013-09-28 12:46:21 +02:00
introduce kern_path_mountpoint()
2013-09-08 20:20:23 -04:00
net: introduce new macro net_get_random_once
2013-10-19 19:45:35 -04:00
ipip: add GSO/TSO support
2013-10-19 19:36:19 -04:00
net: Delete trailing semi-colon from definition of netdev_WARN()
2013-10-18 00:13:21 -04:00
netfilter: add nftables
2013-10-14 17:15:48 +02:00
netfilter: Remove extern from function prototypes
2013-09-26 14:48:15 -07:00
netfilter: Remove extern from function prototypes
2013-09-26 14:48:15 -07:00
netfilter: Remove extern from function prototypes
2013-09-26 14:48:15 -07:00
NFS: Ensure that rmdir() waits for sillyrenames to complete
2013-09-03 15:26:29 -04:00
NFSv4.1 Use MDS auth flavor for data server connection
2013-09-06 14:49:16 -04:00
NFSv4: Honour the 'opened' parameter in the atomic_open() filesystem method
2013-09-26 10:20:18 -04:00
Rename nsproxy.pid_ns to nsproxy.pid_ns_for_children
2013-08-27 13:52:52 -04:00
NVMe: Use normal shutdown
2013-09-03 16:40:32 -04:00
Device tree core updates for v3.12
2013-09-10 13:53:52 -07:00
of/device: add helper to get cpu device node from logical cpu index
2013-08-21 10:29:51 +01:00
Device tree core updates for v3.12
2013-09-10 13:53:52 -07:00
of: clean-up ifdefs in of_irq.h
2013-09-24 21:12:32 -05:00
of: Make of_get_phy_mode() return int i.s.o. const int
2013-08-28 20:50:19 +01:00
drivers: of: add initialization code for dma reserved memory
2013-08-27 10:53:44 +02:00
oprofile: get rid of pointless forward declarations of struct super_block
2013-09-03 22:52:48 -04:00
ARM: SoC platform changes for 3.12
2013-09-06 13:30:06 -07:00
Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next
2013-09-05 14:54:29 -07:00
SCSI misc on 20130915
2013-09-15 17:41:30 -04:00
percpu: Make __verify_pcu_ptr handle per cpu pointers to arrays
2013-08-23 16:08:27 -04:00
idr: Percpu ida
2013-09-09 14:29:15 -07:00
Merge branch 'x86-spinlocks-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2013-09-04 11:55:10 -07:00
power_supply: Prevent suspend until power supply events are processed
2013-08-27 18:42:48 -07:00
PPS: convert class code to use dev_groups
2013-08-19 21:22:34 -07:00
quota: Add a new quotactl command Q_XGETQSTATV
2013-08-20 16:53:58 -05:00
lib/radix-tree.c: make radix_tree_node_alloc() work correctly within interrupt
2013-09-11 15:59:36 -07:00
initmpfs: move rootfs code from fs/ramfs/ to init/
2013-09-11 15:59:37 -07:00
rbtree: add rbtree_postorder_for_each_entry_safe() helper
2013-09-11 15:59:20 -07:00
nohz_full: Add full-system-idle state machine
2013-08-31 14:43:50 -07:00
regmap: Updates for v3.12
2013-09-03 10:07:40 -07:00
memcg: rename RESOURCE_MAX to RES_COUNTER_MAX
2013-09-12 15:38:02 -07:00
mm: memcg: do not trap chargers with full callstack on OOM
2013-09-12 15:38:02 -07:00
seqlock: Add a new locking reader type
2013-09-12 09:25:23 -07:00
DMA: shdma: remove private and unused defines from a global header
2013-08-27 14:25:27 +05:30
sh_eth: remove 'register_type' field from 'struct sh_eth_plat_data'
2013-08-20 17:10:41 -07:00
DMA: shdma: switch DT mode to use configuration data from a match table
2013-08-27 14:25:09 +05:30
shrinker: Kill old ->shrink API.
2013-09-10 18:56:32 -04:00
Introduce [compat_]save_altstack_ex() to unbreak x86 SMAP
2013-09-01 14:16:33 -07:00
ipip: add GSO/TSO support
2013-10-19 19:36:19 -04:00
slab: Use correct GFP_DMA constant
2013-09-04 23:11:42 +03:00
mm/sl[aou]b: Move kmallocXXX functions to common code
2013-09-04 20:51:33 +03:00
slub: remove verify_mem_not_deleted()
2013-09-04 20:53:16 +03:00
watchdog: update watchdog_thresh properly
2013-09-24 17:00:25 -07:00
driver:net:stmmac: Disable DMA store and forward mode if platform data force_thresh_dma_mode is set.
2013-08-30 17:26:09 -04:00
mm: make lru_add_drain_all() selective
2013-09-12 15:38:02 -07:00
syscalls.h: add forward declarations for inplace syscall wrappers
2013-09-11 15:58:25 -07:00
sysfs: sysfs_create_groups returns a value.
2013-08-28 09:51:41 -07:00
tegra-cpuidle: provide stub when !CONFIG_CPU_IDLE
2013-08-29 13:54:34 -07:00
thermal: thermal_core: allow binding with limits on bind_params
2013-09-03 09:10:24 -04:00
timekeeping: Fix HRTICK related deadlock from ntp lock changes
2013-09-12 07:49:51 +02:00
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
2013-09-07 14:35:32 -07:00
gpu/vga_switcheroo: add driver control power feature. (v3)
2013-08-29 13:30:21 +10:00
i915: Update VGA arbiter support for newer devices
2013-09-03 19:17:59 +02:00
mm: vmstats: track TLB flush stats on UP too
2013-09-11 15:57:09 -07:00
Merge branch 'for-3.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
2013-09-03 18:25:03 -07:00
mm: vmscan: fix do_try_to_free_pages() livelock
2013-09-11 15:58:01 -07:00
[SCSI] zfcp: fix lock imbalance by reworking request queue locking
2013-08-22 08:53:30 -07:00
mm/writeback: make writeback_inodes_wb static
2013-09-11 15:58:02 -07:00
