- 20 11月, 2008 5 次提交
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由 Eric Dumazet 提交于
This patch prepares RCU migration of listening_hash table for TCP/DCCP protocols. listening_hash table being small (32 slots per protocol), we add a spinlock for each slot, instead of a single rwlock for whole table. This should reduce hold time of readers, and writers concurrency. Signed-off-by: NEric Dumazet <dada1@cosmosbay.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Stephen Hemminger 提交于
When ethernet devices are converted, the function pointer setup by eth_setup() need to be done during intialization. Signed-off-by: NStephen Hemminger <shemminger@vyatta.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Stephen Hemminger 提交于
In order for the network device ops get_stats call to be immutable, the handling of the default internal network device stats block has to be changed. Add a new helper function which replaces the old use of internal_get_stats. Note: change return code to make it clear that the caller should not go changing the returned statistics. Signed-off-by: NStephen Hemminger <shemminger@vyatta.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Stephen Hemminger 提交于
This patch changes the network device internal API to move adminstrative operations out of the network device structure and into a separate structure. This patch involves some hackery to maintain compatablity between the new and old model, so all 300+ drivers don't have to be changed at once. For drivers that aren't converted yet, the netdevice_ops virt function list still resides in the net_device structure. For old protocols, the new net_device_ops are copied out to the old net_device pointers. After the transistion is completed the nag message can be changed to an WARN_ON, and the compatiablity code can be made configurable. Some function pointers aren't moved: * destructor can't be in net_device_ops because it may need to be referenced after the module is unloaded. * neighbor setup is manipulated in a couple of places that need special consideration * hard_start_xmit is in the fast path for transmit. Signed-off-by: NStephen Hemminger <shemminger@vyatta.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Joe Perches 提交于
The first argument to csum_partial is const void * casts to char/u8 * are not necessary Signed-off-by: NJoe Perches <joe@perches.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 18 11月, 2008 1 次提交
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由 Tejun Heo 提交于
Make add_partition() return pointer to the new hd_struct on success and ERR_PTR() value on failure. This change will be used to fix md autodetection bug. Signed-off-by: NTejun Heo <tj@kernel.org> Cc: Neil Brown <neilb@suse.de> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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- 17 11月, 2008 11 次提交
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由 Alexey Dobriyan 提交于
Simply delete ops from list and let list debugging do the job. Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Gerrit Renker 提交于
This patch deprecates the Ack Ratio sysctl, since * Ack Ratio is entirely ignored by CCID-3 and CCID-4, * Ack Ratio currently doesn't work in CCID-2 (i.e. is always set to 1); * even if it would work in CCID-2, there is no point for a user to change it: - Ack Ratio is constrained by cwnd (RFC 4341, 6.1.2), - if Ack Ratio > cwnd, the system resorts to spurious RTO timeouts (since waiting for Acks which will never arrive in this window), - cwnd is not a user-configurable value. The only reasonable place for Ack Ratio is to print it for debugging. It is planned to do this later on, as part of e.g. dccp_probe. With this patch Ack Ratio is now under full control of feature negotiation: * Ack Ratio is resolved as a dependency of the selected CCID; * if the chosen CCID supports it (i.e. CCID == CCID-2), Ack Ratio is set to the default of 2, following RFC 4340, 11.3 - "New connections start with Ack Ratio 2 for both endpoints"; * what happens then is part of another patch set, since it concerns the dynamic update of Ack Ratio while the connection is in full flight. Thanks to Tomasz Grobelny for discussion leading up to this patch. Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk> Acked-by: NArnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Gerrit Renker 提交于
This provides feature negotiation for server minimum checksum coverage which so far has been missing. Since sender/receiver coverage values range only from 0...15, their type has also been reduced in size from u16 to u4. Feature-negotiation options are now generated for both sender and receiver coverage, i.e. when the peer has `forgotten' to enable partial coverage then feature negotiation will automatically enable (negotiate) the partial coverage value for this connection. Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk> Acked-by: NIan McDonald <ian.mcdonald@jandi.co.nz> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Gerrit Renker 提交于
The previous setsockopt interface, which passed socket options via struct dccp_so_feat, is complicated/difficult to use. Continuing to support it leads to ugly code since the old approach did not distinguish between NN and SP values. This patch removes the old setsockopt interface and replaces it with two new functions to register NN/SP values for feature negotiation. These are essentially wrappers around the internal __feat_register functions, with checking added to avoid * wrong usage (type); * changing values while the connection is in progress. Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Mark McLoughlin 提交于
If segmentation offload is enabled by the host, we currently allocate maximum sized packet buffers and pass them to the host. This uses up 20 ring entries, allowing us to supply only 20 packet buffers to the host with a 256 entry ring. This is a huge overhead when receiving small packets, and is most keenly felt when receiving MTU sized packets from off-host. The VIRTIO_NET_F_MRG_RXBUF feature flag is set by hosts which support using receive buffers which are smaller than the maximum packet size. In order to transfer large packets to the guest, the host merges together multiple receive buffers to form a larger logical buffer. The number of merged buffers is returned to the guest via a field in the virtio_net_hdr. Make use of this support by supplying single page receive buffers to the host. On receive, we extract the virtio_net_hdr, copy 128 bytes of the payload to the skb's linear data buffer and adjust the fragment offset to point to the remaining data. This ensures proper alignment and allows us to not use any paged data for small packets. If the payload occupies multiple pages, we simply append those pages as fragments and free the associated skbs. This scheme allows us to be efficient in our use of ring entries while still supporting large packets. Benchmarking using netperf from an external machine to a guest over a 10Gb/s network shows a 100% improvement from ~1Gb/s to ~2Gb/s. With a local host->guest benchmark with GSO disabled on the host side, throughput was seen to increase from 700Mb/s to 1.7Gb/s. Based on a patch from Herbert Xu. Signed-off-by: NMark McLoughlin <markmc@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (use netdev_priv) Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Eric Dumazet 提交于
As found in the past (commit f1dd9c37 [NET]: Fix tbench regression in 2.6.25-rc1), it is really important that struct dst_entry refcount is aligned on a cache line. We cannot use __atribute((aligned)), so manually pad the structure for 32 and 64 bit arches. for 32bit : offsetof(truct dst_entry, __refcnt) is 0x80 for 64bit : offsetof(truct dst_entry, __refcnt) is 0xc0 As it is not possible to guess at compile time cache line size, we use a generic value of 64 bytes, that satisfies many current arches. (Using 128 bytes alignment on 64bit arches would waste 64 bytes) Add a BUILD_BUG_ON to catch future updates to "struct dst_entry" dont break this alignment. "tbench 8" is 4.4 % faster on a dual quad core (HP BL460c G1), Intel E5450 @3.00GHz (2350 MB/s instead of 2250 MB/s) Signed-off-by: NEric Dumazet <dada1@cosmosbay.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Eric Dumazet 提交于
RCU was added to UDP lookups, using a fast infrastructure : - sockets kmem_cache use SLAB_DESTROY_BY_RCU and dont pay the price of call_rcu() at freeing time. - hlist_nulls permits to use few memory barriers. This patch uses same infrastructure for TCP/DCCP established and timewait sockets. Thanks to SLAB_DESTROY_BY_RCU, no slowdown for applications using short lived TCP connections. A followup patch, converting rwlocks to spinlocks will even speedup this case. __inet_lookup_established() is pretty fast now we dont have to dirty a contended cache line (read_lock/read_unlock) Only established and timewait hashtable are converted to RCU (bind table and listen table are still using traditional locking) Signed-off-by: NEric Dumazet <dada1@cosmosbay.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Eric Dumazet 提交于
This is a straightforward patch, using hlist_nulls infrastructure. RCUification already done on UDP two weeks ago. Using hlist_nulls permits us to avoid some memory barriers, both at lookup time and delete time. Patch is large because it adds new macros to include/net/sock.h. These macros will be used by TCP & DCCP in next patch. Signed-off-by: NEric Dumazet <dada1@cosmosbay.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Eric Dumazet 提交于
hlist uses NULL value to finish a chain. hlist_nulls variant use the low order bit set to 1 to signal an end-of-list marker. This allows to store many different end markers, so that some RCU lockless algos (used in TCP/UDP stack for example) can save some memory barriers in fast paths. Two new files are added : include/linux/list_nulls.h - mimics hlist part of include/linux/list.h, derived to hlist_nulls variant include/linux/rculist_nulls.h - mimics hlist part of include/linux/rculist.h, derived to hlist_nulls variant Only four helpers are declared for the moment : hlist_nulls_del_init_rcu(), hlist_nulls_del_rcu(), hlist_nulls_add_head_rcu() and hlist_nulls_for_each_entry_rcu() prefetches() were removed, since an end of list is not anymore NULL value. prefetches() could trigger useless (and possibly dangerous) memory transactions. Example of use (extracted from __udp4_lib_lookup()) struct sock *sk, *result; struct hlist_nulls_node *node; unsigned short hnum = ntohs(dport); unsigned int hash = udp_hashfn(net, hnum); struct udp_hslot *hslot = &udptable->hash[hash]; int score, badness; rcu_read_lock(); begin: result = NULL; badness = -1; sk_nulls_for_each_rcu(sk, node, &hslot->head) { score = compute_score(sk, net, saddr, hnum, sport, daddr, dport, dif); if (score > badness) { result = sk; badness = score; } } /* * if the nulls value we got at the end of this lookup is * not the expected one, we must restart lookup. * We probably met an item that was moved to another chain. */ if (get_nulls_value(node) != hash) goto begin; if (result) { if (unlikely(!atomic_inc_not_zero(&result->sk_refcnt))) result = NULL; else if (unlikely(compute_score(result, net, saddr, hnum, sport, daddr, dport, dif) < badness)) { sock_put(result); goto begin; } } rcu_read_unlock(); return result; Signed-off-by: NEric Dumazet <dada1@cosmosbay.com> Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Balazs Scheidler 提交于
In case UDP traffic is redirected to a local UDP socket, the originally addressed destination address/port cannot be recovered with the in-kernel tproxy. This patch adds an IP_RECVORIGDSTADDR sockopt that enables a IP_ORIGDSTADDR ancillary message in recvmsg(). This ancillary message contains the original destination address/port of the packet being received. Signed-off-by: NBalazs Scheidler <bazsi@balabit.hu> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Paulius Zaleckas 提交于
make mdio-gpio work with non OpenFirmware gpio implementation. Aditional changes to mdio-gpio: - use gpio_request() and gpio_free() - place irq[] array in struct mdio_gpio_info - add module description, author and license - add note about compiling this driver as module - rename mdc and mdio function (were ugly names) - change MII to MDIO in bus name - add __init __exit to module (un)loading functions - probe fails if no phys added to the bus - kzalloc bitbang with sizeof(*bitbang) Changes since v3: - keep bus naming "%x" to be compatible with existing drivers. Changes since v2: - more #ifdefs reduction - platform driver will be registered on OF platforms also - unified platform and OF bus_id to phy%i Changes since v1: - removed NO_IRQ - reduced #idefs Laurent, please test this driver under OF. Signed-off-by: NPaulius Zaleckas <paulius.zaleckas@teltonika.lt> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 16 11月, 2008 2 次提交
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由 Al Viro 提交于
Inotify watch removals suck violently. To kick the watch out we need (in this order) inode->inotify_mutex and ih->mutex. That's fine if we have a hold on inode; however, for all other cases we need to make damn sure we don't race with umount. We can *NOT* just grab a reference to a watch - inotify_unmount_inodes() will happily sail past it and we'll end with reference to inode potentially outliving its superblock. Ideally we just want to grab an active reference to superblock if we can; that will make sure we won't go into inotify_umount_inodes() until we are done. Cleanup is just deactivate_super(). However, that leaves a messy case - what if we *are* racing with umount() and active references to superblock can't be acquired anymore? We can bump ->s_count, grab ->s_umount, which will almost certainly wait until the superblock is shut down and the watch in question is pining for fjords. That's fine, but there is a problem - we might have hit the window between ->s_active getting to 0 / ->s_count - below S_BIAS (i.e. the moment when superblock is past the point of no return and is heading for shutdown) and the moment when deactivate_super() acquires ->s_umount. We could just do drop_super() yield() and retry, but that's rather antisocial and this stuff is luser-triggerable. OTOH, having grabbed ->s_umount and having found that we'd got there first (i.e. that ->s_root is non-NULL) we know that we won't race with inotify_umount_inodes(). So we could grab a reference to watch and do the rest as above, just with drop_super() instead of deactivate_super(), right? Wrong. We had to drop ih->mutex before we could grab ->s_umount. So the watch could've been gone already. That still can be dealt with - we need to save watch->wd, do idr_find() and compare its result with our pointer. If they match, we either have the damn thing still alive or we'd lost not one but two races at once, the watch had been killed and a new one got created with the same ->wd at the same address. That couldn't have happened in inotify_destroy(), but inotify_rm_wd() could run into that. Still, "new one got created" is not a problem - we have every right to kill it or leave it alone, whatever's more convenient. So we can use idr_find(...) == watch && watch->inode->i_sb == sb as "grab it and kill it" check. If it's been our original watch, we are fine, if it's a newcomer - nevermind, just pretend that we'd won the race and kill the fscker anyway; we are safe since we know that its superblock won't be going away. And yes, this is far beyond mere "not very pretty"; so's the entire concept of inotify to start with. Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk> Acked-by: NGreg KH <greg@kroah.com> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Martin Schwidefsky 提交于
A common reason for device drivers to implement their own printk macros is the lack of a printk prefix with the standard pr_xyz macros. Introduce a pr_fmt() macro that is applied for every pr_xyz macro to the format string. The most common use of the pr_fmt macro would be to add the name of the device driver to all pr_xyz messages in a source file. Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 14 11月, 2008 5 次提交
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由 Ingo Molnar 提交于
fix this warning: net/bluetooth/af_bluetooth.c:60: warning: ‘bt_key_strings’ defined but not used net/bluetooth/af_bluetooth.c:71: warning: ‘bt_slock_key_strings’ defined but not used this is a lockdep macro problem in the !LOCKDEP case. We cannot convert it to an inline because the macro works on multiple types, but we can mark the parameter used. [ also clean up a misaligned tab in sock_lock_init_class_and_name() ] [ also remove #ifdefs from around af_family_clock_key strings - which were certainly added to get rid of the ugly build warnings. ] Signed-off-by: NIngo Molnar <mingo@elte.hu> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Jarek Poplawski 提交于
After implementing qdisc->ops->peek() and changing sch_netem into classless qdisc there are no more qdisc->ops->requeue() users. This patch removes this method with its wrappers (qdisc_requeue()), and also unused qdisc->requeue structure. There are a few minor fixes of warnings (htb_enqueue()) and comments btw. The idea to kill ->requeue() and a similar patch were first developed by David S. Miller. Signed-off-by: NJarek Poplawski <jarkao2@gmail.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Petr Tesarik 提交于
The urg_ptr field is not used anywhere and is merely confusing. Signed-off-by: NPetr Tesarik <ptesarik@suse.cz> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Alan Stern 提交于
This patch (as1155) fixes a bug in usbcore. When interfaces are deleted, either because the device was disconnected or because of a configuration change, the extra attribute files and child endpoint devices may get left behind. This is because the core removes them before calling device_del(). But during device_del(), after the driver is unbound the core will reinstall altsetting 0 and recreate those extra attributes and children. The patch prevents this by adding a flag to record when the interface is in the midst of being unregistered. When the flag is set, the attribute files and child devices will not be created. Signed-off-by: NAlan Stern <stern@rowland.harvard.edu> Cc: stable <stable@kernel.org> [2.6.27, 2.6.26, 2.6.25] Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>
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由 Peter Zijlstra 提交于
Explain this SLAB_DESTROY_BY_RCU thing... [hugh@veritas.com: add a pointer to comment in mm/slab.c] Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: NJens Axboe <jens.axboe@oracle.com> Acked-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: NChristoph Lameter <cl@linux-foundation.org> Signed-off-by: NHugh Dickins <hugh@veritas.com> Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>
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- 13 11月, 2008 6 次提交
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由 Henrik Rydberg 提交于
On macbooks there are specific keys for the user-space functions Expose and Dashboard, which currently has no counterpart in input.h. This patch adds KEY_SCALE and KEY_DASHBOARD, and maps the keyboard accordingly. Acked-by: NDmitry Torokhov <dmitry.torokhov@gmail.com> Signed-off-by: NHenrik Rydberg <rydberg@euromail.se> Signed-off-by: NJiri Kosina <jkosina@suse.cz>
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由 Alexey Dobriyan 提交于
Every user is under CONFIG_NET_DMA already, so ifdef field as well. Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Rodolfo Giometti 提交于
C2port implements a two wire serial communication protocol (bit banging) designed to enable in-system programming, debugging, and boundary-scan testing on low pin-count Silicon Labs devices. Currently this code supports only flash programming through sysfs interface but extensions shoud be easy to add. Signed-off-by: NRodolfo Giometti <giometti@linux.it> Cc: Greg KH <greg@kroah.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Mark Brown 提交于
This adds support for the RTC provided by the Wolfson Microelectronics WM8350. This driver was originally written by Graeme Gregory and Liam Girdwood, though it has been modified since then to update it to current mainline coding standards and for API completeness. [akpm@linux-foundation.org: s/schedule_timeout_interruptible/schedule_timeout_uninterruptible/ to prevent bogus timeout when signal_pending()] Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com> Cc: Alessandro Zummo <a.zummo@towertech.it> Cc: David Brownell <david-b@pacbell.net> Cc: Liam Girdwood <linux@wolfsonmicro.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Andrew Morton 提交于
It mistakenly assumes that a static local in an inlined function is a kernel-wide singleton. It also has no callers, so let's remove it. Cc: Dave Young <hidave.darkstar@gmail.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Nicolas Ferre 提交于
Changed because old the definition of unsigned long cannot be negative. Signed-off-by: NNicolas Ferre <nicolas.ferre@atmel.com> Reported-by: NRoel Kluin <roel.kluin@gmail.com> Cc: Haavard Skinnemoen <hskinnemoen@atmel.com> Cc: Andrew Victor <linux@maxim.org.za> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 12 11月, 2008 10 次提交
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由 Eric Dumazet 提交于
Using read_pnet() and write_pnet() in neighbour code ease the reading of code. Signed-off-by: NEric Dumazet <dada1@cosmosbay.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Peter Zijlstra 提交于
Impact: cleanup git grep HRTIMER_CB_IRQSAFE revealed half the callback modes are actually unused. Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Eric Dumazet 提交于
We can shrink size of "struct inet_bind_bucket" by 50%, using read_pnet() and write_pnet() Signed-off-by: NEric Dumazet <dada1@cosmosbay.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Eric Dumazet 提交于
This patch introduces two helpers that deal with reading and writing struct net pointers in various network structures. Their implementation depends on CONFIG_NET_NS For symmetry, both functions work with "struct net **pnet". Their usage should reduce the number of #ifdef CONFIG_NET_NS, without adding many helpers for each network structure that hold a "struct net *pointer" Signed-off-by: NEric Dumazet <dada1@cosmosbay.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Gerrit Renker 提交于
This provides a data structure to record which CCIDs are locally supported and three accessor functions: - a test function for internal use which is used to validate CCID requests made by the user; - a copy function so that the list can be used for feature-negotiation; - documented getsockopt() support so that the user can query capabilities. The data structure is a table which is filled in at compile-time with the list of available CCIDs (which in turn depends on the Kconfig choices). Using the copy function for cloning the list of supported CCIDs is useful for feature negotiation, since the negotiation is now with the full list of available CCIDs (e.g. {2, 3}) instead of the default value {2}. This means negotiation will not fail if the peer requests to use CCID3 instead of CCID2. Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk> Acked-by: NIan McDonald <ian.mcdonald@jandi.co.nz> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Yoshihiro Shimoda 提交于
SH7723 has SCIFA. This module is similer SCI register map, but it has FIFO. So this patch adds new type(PORT_SCIFA) and change some type checking. Signed-off-by: NYoshihiro Shimoda <shimoda.yoshihiro@renesas.com> Signed-off-by: NPaul Mundt <lethal@linux-sh.org>
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由 Alexey Dobriyan 提交于
Unused after kmem_cache_zalloc() conversion. Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Alexey Dobriyan 提交于
->pde isn't actually needed, since name is stashed in ->id. Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Alexey Starikovskiy 提交于
Disabling gpe might interfere with gpe detection/handling, thus producing "interrupt not handled" errors. Ironically, disabling of GPE from interrupt context is already under spinlock, so only userspace needs to start using it. Signed-off-by: NAlexey Starikovskiy <astarikovskiy@suse.de> Signed-off-by: NLen Brown <len.brown@intel.com>
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由 Steven Rostedt 提交于
Impact: enable/disable ring buffer recording API added Several kernel developers have requested that there be a way to stop recording into the ring buffers with a simple switch that can also be enabled from userspace. This patch addes a new kernel API to the ring buffers called: tracing_on() tracing_off() When tracing_off() is called, all ring buffers will not be able to record into their buffers. tracing_on() will enable the ring buffers again. These two act like an on/off switch. That is, there is no counting of the number of times tracing_off or tracing_on has been called. A new file is added to the debugfs/tracing directory called tracing_on This allows for userspace applications to also flip the switch. echo 0 > debugfs/tracing/tracing_on disables the tracing. echo 1 > /debugfs/tracing/tracing_on enables it. Note, this does not disable or enable any tracers. It only sets or clears a flag that needs to be set in order for the ring buffers to write to their buffers. It is a global flag, and affects all ring buffers. The buffers start out with tracing_on enabled. There are now three flags that control recording into the buffers: tracing_on: which affects all ring buffer tracers. buffer->record_disabled: which affects an allocated buffer, which may be set if an anomaly is detected, and tracing is disabled. cpu_buffer->record_disabled: which is set by tracing_stop() or if an anomaly is detected. tracing_start can not reenable this if an anomaly occurred. The userspace debugfs/tracing/tracing_enabled is implemented with tracing_stop() but the user space code can not enable it if the kernel called tracing_stop(). Userspace can enable the tracing_on even if the kernel disabled it. It is just a switch used to stop tracing if a condition was hit. tracing_on is not for protecting critical areas in the kernel nor is it for stopping tracing if an anomaly occurred. This is because userspace can reenable it at any time. Side effect: With this patch, I discovered a dead variable in ftrace.c called tracing_on. This patch removes it. Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
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