- 06 2月, 2015 18 次提交
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由 Jon Paul Maloy 提交于
TIPC handles message cardinality and sequencing at the link layer, before passing messages upwards to the destination sockets. During the upcall from link to socket no locks are held. It is therefore possible, and we see it happen occasionally, that messages arriving in different threads and delivered in sequence still bypass each other before they reach the destination socket. This must not happen, since it violates the sequentiality guarantee. We solve this by adding a new input buffer queue to the link structure. Arriving messages are added safely to the tail of that queue by the link, while the head of the queue is consumed, also safely, by the receiving socket. Sequentiality is secured per socket by only allowing buffers to be dequeued inside the socket lock. Since there may be multiple simultaneous readers of the queue, we use a 'filter' parameter to reduce the risk that they peek the same buffer from the queue, hence also reducing the risk of contention on the receiving socket locks. This solves the sequentiality problem, and seems to cause no measurable performance degradation. A nice side effect of this change is that lock handling in the functions tipc_rcv() and tipc_bcast_rcv() now becomes uniform, something that will enable future simplifications of those functions. Reviewed-by: NYing Xue <ying.xue@windriver.com> Signed-off-by: NJon Maloy <jon.maloy@ericsson.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Jon Paul Maloy 提交于
The list for outgoing traffic buffers from a socket is currently allocated on the stack. This forces us to initialize the queue for each sent message, something costing extra CPU cycles in the most critical data path. Later in this series we will introduce a new safe input buffer queue, something that would force us to initialize even the spinlock of the outgoing queue. A closer analysis reveals that the queue always is filled and emptied within the same lock_sock() session. It is therefore safe to use a queue aggregated in the socket itself for this purpose. Since there already exists a queue for this in struct sock, sk_write_queue, we introduce use of that queue in this commit. Reviewed-by: NYing Xue <ying.xue@windriver.com> Signed-off-by: NJon Maloy <jon.maloy@ericsson.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Jon Paul Maloy 提交于
The function tipc_msg_eval() is in reality doing two related, but different tasks. First it tries to find a new destination for named messages, in case there was no first lookup, or if the first lookup failed. Second, it does what its name suggests, evaluating the validity of the message and its destination, and returning an appropriate error code depending on the result. This is confusing, and in this commit we choose to break it up into two functions. A new function, tipc_msg_lookup_dest(), first attempts to find a new destination, if the message is of the right type. If this lookup fails, or if the message should not be subject to a second lookup, the already existing tipc_msg_reverse() is called. This function performs prepares the message for rejection, if applicable. Reviewed-by: NYing Xue <ying.xue@windriver.com> Signed-off-by: NJon Maloy <jon.maloy@ericsson.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Jon Paul Maloy 提交于
The code for enqueuing arriving buffers in the function tipc_sk_rcv() contains long code lines and currently goes to two indentation levels. As a cosmetic preparaton for the next commits, we break it out into a separate function. Reviewed-by: NYing Xue <ying.xue@windriver.com> Signed-off-by: NJon Maloy <jon.maloy@ericsson.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Jon Paul Maloy 提交于
Despite recent improvements, the handling of error codes and return values at reception of messages in the socket layer is still confusing. In this commit, we try to make it more comprehensible. First, we separate between the return values coming from the functions called by tipc_sk_rcv(), -those are TIPC specific error codes, and the return values returned by tipc_sk_rcv() itself. Second, we don't use the returned TIPC error code as indication for whether a buffer should be forwarded/rejected or not; instead we use the buffer pointer passed along with filter_msg(). This separation is necessary because we sometimes want to forward messages even when there is no error (i.e., protocol messages and successfully secondary looked up data messages). Reviewed-by: NYing Xue <ying.xue@windriver.com> Signed-off-by: NJon Maloy <jon.maloy@ericsson.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Jon Paul Maloy 提交于
The most common usage of namespace information is when we fetch the own node addess from the net structure. This leads to a lot of passing around of a parameter of type 'struct net *' between functions just to make them able to obtain this address. However, in many cases this is unnecessary. The own node address is readily available as a member of both struct tipc_sock and tipc_link, and can be fetched from there instead. The fact that the vast majority of functions in socket.c and link.c anyway are maintaining a pointer to their respective base structures makes this option even more compelling. In this commit, we introduce the inline functions tsk_own_node() and link_own_node() to make it easy for functions to fetch the node address from those structs instead of having to pass along and dereference the namespace struct. In particular, we make calls to the msg_xx() functions in msg.{h,c} context independent by directly passing them the own node address as parameter when needed. Those functions should be regarded as leaves in the code dependency tree, and it is hence desirable to keep them namspace unaware. Apart from a potential positive effect on cache behavior, these changes make it easier to introduce the changes that will follow later in this series. Reviewed-by: NYing Xue <ying.xue@windriver.com> Signed-off-by: NJon Maloy <jon.maloy@ericsson.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Takashi Iwai 提交于
Pass the static attribute groups and the driver data via tty_port_register_device_attr() instead of manual device_create_file() and device_remove_file() calls. Signed-off-by: NTakashi Iwai <tiwai@suse.de> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
Bas Peters says: ==================== Fix checkpatch errors in drivers/isdn/isdnloop This patchset adresses various checkpatch errors in the abovementioned driver. ==================== Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Bas Peters 提交于
drivers: isdn: isdnloop: isdnloop.c: Remove parenthesis around return values, as specified in CodingStyle. Signed-off-by: NBas Peters <baspeters93@gmail.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Bas Peters 提交于
Signed-off-by: NBas Peters <baspeters93@gmail.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Bas Peters 提交于
drivers: isdn: isdnloop: isdnloop.c: remove assignment of variables in if conditions, in accordance with the CodingStyle. Signed-off-by: NBas Peters <baspeters93@gmail.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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git://git.kernel.org/pub/scm/linux/kernel/git/davem/net由 David S. Miller 提交于
Conflicts: drivers/net/vxlan.c drivers/vhost/net.c include/linux/if_vlan.h net/core/dev.c The net/core/dev.c conflict was the overlap of one commit marking an existing function static whilst another was adding a new function. In the include/linux/if_vlan.h case, the type used for a local variable was changed in 'net', whereas the function got rewritten to fix a stacked vlan bug in 'net-next'. In drivers/vhost/net.c, Al Viro's iov_iter conversions in 'net-next' overlapped with an endainness fix for VHOST 1.0 in 'net'. In drivers/net/vxlan.c, vxlan_find_vni() added a 'flags' parameter in 'net-next' whereas in 'net' there was a bug fix to pass in the correct network namespace pointer in calls to this function. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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git://git.kernel.org/pub/scm/linux/kernel/git/davem/net由 Linus Torvalds 提交于
Pull networking fixes from David Miller: 1) Stretch ACKs can kill performance with Reno and CUBIC congestion control, largely due to LRO and GRO. Fix from Neal Cardwell. 2) Fix userland breakage because we accidently emit zero length netlink messages from the bridging code. From Roopa Prabhu. 3) Carry handling in generic csum_tcpudp_nofold is broken, fix from Karl Beldan. 4) Remove bogus dev_set_net() calls from CAIF driver, from Nicolas Dichtel. 5) Make sure PPP deflation never returns a length greater then the output buffer, otherwise we overflow and trigger skb_over_panic(). Fix from Florian Westphal. 6) COSA driver needs VIRT_TO_BUS Kconfig dependencies, from Arnd Bergmann. 7) Don't increase route cached MTU on datagram too big ICMPs. From Li Wei. 8) Fix error path leaks in nf_tables, from Pablo Neira Ayuso. 9) Fix bitmask handling regression in netlink that broke things like acpi userland tools. From Pablo Neira Ayuso. 10) Wrong header pointer passed to param_type2af() in SCTP code, from Saran Maruti Ramanara. 11) Stacked vlans not handled correctly by vlan_get_protocol(), from Toshiaki Makita. 12) Add missing DMA memory barrier to xgene driver, from Iyappan Subramanian. 13) Fix crash in rate estimators, from Eric Dumazet. 14) We've been adding various workarounds, one after another, for the change which added the per-net tcp_sock. It was meant to reduce socket contention but added lots of problems. Reduce this instead to a proper per-cpu socket and that rids us of all the daemons. From Eric Dumazet. 15) Fix memory corruption and OOPS in mlx4 driver, from Jack Morgenstein. 16) When we disabled UFO in the virtio_net device, it introduces some serious performance regressions. The orignal problem was IPV6 fragment ID generation, so fix that properly instead. From Vlad Yasevich. 17) sr9700 driver build breaks on xtensa because it defines macros with the same name as those used by the arch code. Use more unique names. From Chen Gang. 18) Fix endianness in new virio 1.0 mode of the vhost net driver, from Michael S Tsirkin. 19) Several sysctls were setting the maxlen attribute incorrectly, from Sasha Levin. 20) Don't accept an FQ scheduler quantum of zero, that leads to crashes. From Kenneth Klette Jonassen. 21) Fix dumping of non-existing actions in the packet scheduler classifier. From Ignacy Gawędzki. 22) Return the write work_done value when doing TX work in the qlcnic driver. 23) ip6gre_err accesses the info field with the wrong endianness, from Sabrina Dubroca. * git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (54 commits) sit: fix some __be16/u16 mismatches ipv6: fix sparse errors in ip6_make_flowlabel() net: remove some sparse warnings flow_keys: n_proto type should be __be16 ip6_gre: fix endianness errors in ip6gre_err qlcnic: Fix NAPI poll routine for Tx completion amd-xgbe: Set RSS enablement based on hardware features amd-xgbe: Adjust for zero-based traffic class count cls_api.c: Fix dumping of non-existing actions' stats. pkt_sched: fq: avoid hang when quantum 0 net: rds: use correct size for max unacked packets and bytes vhost/net: fix up num_buffers endian-ness gianfar: correct the bad expression while writing bit-pattern net: usb: sr9700: Use 'SR_' prefix for the common register macros Revert "drivers/net: Disable UFO through virtio" Revert "drivers/net, ipv6: Select IPv6 fragment idents for virtio UFO packets" ipv6: Select fragment id during UFO segmentation if not set. xen-netback: stop the guest rx thread after a fatal error net/mlx4_core: Fix kernel Oops (mem corruption) when working with more than 80 VFs isdn: off by one in connect_res() ...
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git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi由 Linus Torvalds 提交于
Pull SCSI fixes from James Bottomley: "This patch set is fixing two serious problems which have turned up late in the release cycle. The first fixes a problem with 4k sector disks where the transfer length (amount of data sent to the disk) was getting increased every time the disk was revalidated leading to potential for overflows. The other is a regression oops fix for some of our last merge window code" * tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: sd: Fix max transfer length for 4k disks scsi: fix device handler detach oops
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git://people.freedesktop.org/~airlied/linux由 Linus Torvalds 提交于
Pull drm fixes from Dave Airlie: "Radeon and amdkfd fixes. Radeon ones mostly for oops in some test/benchmark functions since fencing changes, and one regression fix for old GPUs, There is one cirrus regression fix, the 32bpp broke userspace, so this hides it behind a module option for the few users who care. I'm off for a few days, so this is probably the final pull I have, if I see fixes from Intel I'll forward the pull as I should have email" * 'drm-fixes' of git://people.freedesktop.org/~airlied/linux: drm/cirrus: Limit modes depending on bpp option drm/radeon: fix the crash in test functions drm/radeon: fix the crash in benchmark functions drm/radeon: properly set vm fragment size for TN/RL drm/radeon: don't init gpuvm if accel is disabled (v3) drm/radeon: fix PLLs on RS880 and older v2 drm/amdkfd: Don't create BUG due to incorrect user parameter drm/amdkfd: max num of queues can't be 0 drm/amdkfd: Fix bug in accounting of queues
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git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi由 Linus Torvalds 提交于
Pull spi fixes from Mark Brown: "A couple of driver specific fixes: - Disable DMA mode for i.MX6DL chips due to a hardware bug. - Don't use devm_kzalloc() outside of bind/unbind paths in the fsl-dspi driver, fixing memory leaks" * tag 'spi-v3.19-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi: spi: imx: use pio mode for i.mx6dl spi: spi-fsl-dspi: Remove usage of devm_kzalloc
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git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm由 Linus Torvalds 提交于
Pull ACPI power management fix from Rafael Wysocki: "This is a revert of an ACPI Low-power Subsystem (LPSS) driver change that was supposed to improve power management of the LPSS DMA controller, but introduced more serious problems. Since fixing them turns out to be non-trivial, it is better to revert the commit in question at this point and try to fix the original issue differently in the next cycle" * tag 'pm+acpi-3.19-fin' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: Revert "ACPI / LPSS: introduce a 'proxy' device to power on LPSS for DMA"
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git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci由 Linus Torvalds 提交于
Pull PCI fixes from Bjorn Helgaas: "Enumeration - Scan all device numbers on NEC as well as Stratus (Charlotte Richardson) Resource management - Handle read-only BARs on AMD CS553x devices (Myron Stowe) Synopsys DesignWare - Reject MSI-X IRQs (Lucas Stach)" * tag 'pci-v3.19-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci: PCI: Handle read-only BARs on AMD CS553x devices PCI: Add NEC variants to Stratus ftServer PCIe DMI check PCI: designware: Reject MSI-X IRQs
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- 05 2月, 2015 22 次提交
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由 Eric Dumazet 提交于
Fixes following sparse warnings : net/ipv6/sit.c:1509:32: warning: incorrect type in assignment (different base types) net/ipv6/sit.c:1509:32: expected restricted __be16 [usertype] sport net/ipv6/sit.c:1509:32: got unsigned short net/ipv6/sit.c:1514:32: warning: incorrect type in assignment (different base types) net/ipv6/sit.c:1514:32: expected restricted __be16 [usertype] dport net/ipv6/sit.c:1514:32: got unsigned short net/ipv6/sit.c:1711:38: warning: incorrect type in argument 3 (different base types) net/ipv6/sit.c:1711:38: expected unsigned short [unsigned] [usertype] value net/ipv6/sit.c:1711:38: got restricted __be16 [usertype] sport net/ipv6/sit.c:1713:38: warning: incorrect type in argument 3 (different base types) net/ipv6/sit.c:1713:38: expected unsigned short [unsigned] [usertype] value net/ipv6/sit.c:1713:38: got restricted __be16 [usertype] dport Signed-off-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Eric Dumazet 提交于
include/net/ipv6.h:713:22: warning: incorrect type in assignment (different base types) include/net/ipv6.h:713:22: expected restricted __be32 [usertype] hash include/net/ipv6.h:713:22: got unsigned int include/net/ipv6.h:719:25: warning: restricted __be32 degrades to integer include/net/ipv6.h:719:22: warning: invalid assignment: ^= include/net/ipv6.h:719:22: left side has type restricted __be32 include/net/ipv6.h:719:22: right side has type unsigned int Signed-off-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Eric Dumazet 提交于
netdev_adjacent_add_links() and netdev_adjacent_del_links() are static. queue->qdisc has __rcu annotation, need to use RCU_INIT_POINTER() Signed-off-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Eric Dumazet 提交于
(struct flow_keys)->n_proto is in network order, use proper type for this. Fixes following sparse errors : net/core/flow_dissector.c:139:39: warning: incorrect type in assignment (different base types) net/core/flow_dissector.c:139:39: expected unsigned short [unsigned] [usertype] n_proto net/core/flow_dissector.c:139:39: got restricted __be16 [assigned] [usertype] proto net/core/flow_dissector.c:237:23: warning: incorrect type in assignment (different base types) net/core/flow_dissector.c:237:23: expected unsigned short [unsigned] [usertype] n_proto net/core/flow_dissector.c:237:23: got restricted __be16 [assigned] [usertype] proto Signed-off-by: NEric Dumazet <edumazet@google.com> Fixes: e0f31d84 ("flow_keys: Record IP layer protocol in skb_flow_dissect()") Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Thomas Graf 提交于
This allows for a VXLAN-GBP socket to talk to a Linux VXLAN socket by not setting any of the bits. Signed-off-by: NThomas Graf <tgraf@suug.ch> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Markus Elfring 提交于
The kfree() function tests whether its argument is NULL and then returns immediately. Thus the test around the call is not needed. This issue was detected by using the Coccinelle software. Signed-off-by: NMarkus Elfring <elfring@users.sourceforge.net> Signed-off-by: NH Hartley Sweeten <hsweeten@visionengravers.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Sabrina Dubroca 提交于
info is in network byte order, change it back to host byte order before use. In particular, the current code sets the MTU of the tunnel to a wrong (too big) value. Fixes: c12b395a ("gre: Support GRE over IPv6") Signed-off-by: NSabrina Dubroca <sd@queasysnail.net> Acked-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Takashi Iwai 提交于
Instead of manual calls of device_create_file() and device_remove_files(), assign the static attribute groups to netdev groups array. This simplifies the code and avoids the possible races. Signed-off-by: NTakashi Iwai <tiwai@suse.de> Acked-by: NDavid Vrabel <david.vrabel@citrix.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Takashi Iwai 提交于
Instead of manual calls of device_create_file() and device_remove_files(), assign the static attribute groups to netdev groups array. This simplifies the code and avoids the possible races. Signed-off-by: NTakashi Iwai <tiwai@suse.de> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Markus Elfring 提交于
The functions kfree() and vfree() perform also input parameter validation. Thus the test around their calls is not needed. This issue was detected by using the Coccinelle software. Signed-off-by: NMarkus Elfring <elfring@users.sourceforge.net> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
Merge tag 'linux-can-next-for-3.20-20150204' of git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can-next Marc Kleine-Budde says: ==================== pull-request: can-next 2015-02-04 this is a pull request of 2 patches for net-next/master. Nicholas Mc Guire contributes a patch for the janz-ican3 driver to fix a mismatch in an assignment. Ahmed S. Darwish contributes a patch for the kvaser_usb driver, to make the driver more robust during the bus-off handling. ==================== Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Lad, Prabhakar 提交于
this patch fixes following sparse warning: cpsw-common.c:23:5: warning: symbol 'cpsw_am33xx_cm_get_macid' was not declared. Should it be static? Signed-off-by: NLad, Prabhakar <prabhakar.csengg@gmail.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Markus Elfring 提交于
The kfree() function tests whether its argument is NULL and then returns immediately. Thus the test around the call is not needed. This issue was detected by using the Coccinelle software. Signed-off-by: NMarkus Elfring <elfring@users.sourceforge.net> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Markus Elfring 提交于
The kfree() function tests whether its argument is NULL and then returns immediately. Thus the test around the call is not needed. This issue was detected by using the Coccinelle software. Signed-off-by: NMarkus Elfring <elfring@users.sourceforge.net> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Markus Elfring 提交于
The kfree() function tests whether its argument is NULL and then returns immediately. Thus the test around the call is not needed. This issue was detected by using the Coccinelle software. Signed-off-by: NMarkus Elfring <elfring@users.sourceforge.net> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Shahed Shaikh 提交于
After d75b1ade ("net: less interrupt masking in NAPI") driver's NAPI poll routine is expected to return exact budget value if it wants to be re-called. Signed-off-by: NShahed Shaikh <shahed.shaikh@qlogic.com> Fixes: d75b1ade ("net: less interrupt masking in NAPI") Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Markus Elfring 提交于
The release_firmware() function tests whether its argument is NULL and then returns immediately. Thus the test around the call is not needed. This issue was detected by using the Coccinelle software. Signed-off-by: NMarkus Elfring <elfring@users.sourceforge.net> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Hariprasad Shenai 提交于
cxgb_busy_poll, corresponding to ndo_busy_poll, gets called by the socket waiting for data. With busy_poll enabled, improvement is seen in latency numbers as observed by collecting netperf TCP_RR numbers. Below are latency number, with and without busy-poll, in a switched environment for a particular msg size: netperf command: netperf -4 -H <ip> -l 30 -t TCP_RR -- -r1,1 Latency without busy-poll: ~16.25 us Latency with busy-poll : ~08.79 us Based on original work by Kumar Sanghvi <kumaras@chelsio.com> Signed-off-by: NHariprasad Shenai <hariprasad@chelsio.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
Revert "bridge: Let bridge not age 'externally' learnt FDB entries, they are removed when 'external' entity notifies the aging" This reverts commit 9a05dde5. Requested by Scott Feldman. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Eric Dumazet 提交于
FQ has a fast path for skb attached to a socket, as it does not have to compute a flow hash. But for other packets, FQ being non stochastic means that hosts exposed to random Internet traffic can allocate million of flows structure (104 bytes each) pretty easily. Not only host can OOM, but lookup in RB trees can take too much cpu and memory resources. This patch adds a new attribute, orphan_mask, that is adding possibility of having a stochastic hash for orphaned skb. Its default value is 1024 slots, to mimic SFQ behavior. Note: This does not apply to locally generated TCP traffic, and no locally generated traffic will share a flow structure with another perfect or stochastic flow. This patch also handles the specific case of SYNACK messages: They are attached to the listener socket, and therefore all map to a single hash bucket. If listener have set SO_MAX_PACING_RATE, hoping to have new accepted socket inherit this rate, SYNACK might be paced and even dropped. This is very similar to an internal patch Google have used more than one year. Signed-off-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs由 David S. Miller 提交于
More iov_iter work from Al Viro. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Eric Dumazet 提交于
When we added pacing to TCP, we decided to let sch_fq take care of actual pacing. All TCP had to do was to compute sk->pacing_rate using simple formula: sk->pacing_rate = 2 * cwnd * mss / rtt It works well for senders (bulk flows), but not very well for receivers or even RPC : cwnd on the receiver can be less than 10, rtt can be around 100ms, so we can end up pacing ACK packets, slowing down the sender. Really, only the sender should pace, according to its own logic. Instead of adding a new bit in skb, or call yet another flow dissection, we tweak skb->truesize to a small value (2), and we instruct sch_fq to use new helper and not pace pure ack. Note this also helps TCP small queue, as ack packets present in qdisc/NIC do not prevent sending a data packet (RPC workload) This helps to reduce tx completion overhead, ack packets can use regular sock_wfree() instead of tcp_wfree() which is a bit more expensive. This has no impact in the case packets are sent to loopback interface, as we do not coalesce ack packets (were we would detect skb->truesize lie) In case netem (with a delay) is used, skb_orphan_partial() also sets skb->truesize to 1. This patch is a combination of two patches we used for about one year at Google. Signed-off-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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