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authorLinus Torvalds <torvalds@linux-foundation.org>2018-10-24 08:47:44 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2018-10-24 08:47:44 +0300
commit50b825d7e87f4cff7070df6eb26390152bb29537 (patch)
treeec82aba49ab0c4743266ff37e18c8304a0367d06 /tools/include/linux
parenta97a2d4d56ea596871b739d63d41b084733bd9fb (diff)
parent3f80e08f40cdb308589a49077c87632fa4508b21 (diff)
downloadlinux-50b825d7e87f4cff7070df6eb26390152bb29537.tar.xz
Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next
Pull networking updates from David Miller: 1) Add VF IPSEC offload support in ixgbe, from Shannon Nelson. 2) Add zero-copy AF_XDP support to i40e, from Björn Töpel. 3) All in-tree drivers are converted to {g,s}et_link_ksettings() so we can get rid of the {g,s}et_settings ethtool callbacks, from Michal Kubecek. 4) Add software timestamping to veth driver, from Michael Walle. 5) More work to make packet classifiers and actions lockless, from Vlad Buslov. 6) Support sticky FDB entries in bridge, from Nikolay Aleksandrov. 7) Add ipv6 version of IP_MULTICAST_ALL sockopt, from Andre Naujoks. 8) Support batching of XDP buffers in vhost_net, from Jason Wang. 9) Add flow dissector BPF hook, from Petar Penkov. 10) i40e vf --> generic iavf conversion, from Jesse Brandeburg. 11) Add NLA_REJECT netlink attribute policy type, to signal when users provide attributes in situations which don't make sense. From Johannes Berg. 12) Switch TCP and fair-queue scheduler over to earliest departure time model. From Eric Dumazet. 13) Improve guest receive performance by doing rx busy polling in tx path of vhost networking driver, from Tonghao Zhang. 14) Add per-cgroup local storage to bpf 15) Add reference tracking to BPF, from Joe Stringer. The verifier can now make sure that references taken to objects are properly released by the program. 16) Support in-place encryption in TLS, from Vakul Garg. 17) Add new taprio packet scheduler, from Vinicius Costa Gomes. 18) Lots of selftests additions, too numerous to mention one by one here but all of which are very much appreciated. 19) Support offloading of eBPF programs containing BPF to BPF calls in nfp driver, frm Quentin Monnet. 20) Move dpaa2_ptp driver out of staging, from Yangbo Lu. 21) Lots of u32 classifier cleanups and simplifications, from Al Viro. 22) Add new strict versions of netlink message parsers, and enable them for some situations. From David Ahern. 23) Evict neighbour entries on carrier down, also from David Ahern. 24) Support BPF sk_msg verdict programs with kTLS, from Daniel Borkmann and John Fastabend. 25) Add support for filtering route dumps, from David Ahern. 26) New igc Intel driver for 2.5G parts, from Sasha Neftin et al. 27) Allow vxlan enslavement to bridges in mlxsw driver, from Ido Schimmel. 28) Add queue and stack map types to eBPF, from Mauricio Vasquez B. 29) Add back byte-queue-limit support to r8169, with all the bug fixes in other areas of the driver it works now! From Florian Westphal and Heiner Kallweit. * git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (2147 commits) tcp: add tcp_reset_xmit_timer() helper qed: Fix static checker warning Revert "be2net: remove desc field from be_eq_obj" Revert "net: simplify sock_poll_wait" net: socionext: Reset tx queue in ndo_stop net: socionext: Add dummy PHY register read in phy_write() net: socionext: Stop PHY before resetting netsec net: stmmac: Set OWN bit for jumbo frames arm64: dts: stratix10: Support Ethernet Jumbo frame tls: Add maintainers net: ethernet: ti: cpsw: unsync mcast entries while switch promisc mode octeontx2-af: Support for NIXLF's UCAST/PROMISC/ALLMULTI modes octeontx2-af: Support for setting MAC address octeontx2-af: Support for changing RSS algorithm octeontx2-af: NIX Rx flowkey configuration for RSS octeontx2-af: Install ucast and bcast pkt forwarding rules octeontx2-af: Add LMAC channel info to NIXLF_ALLOC response octeontx2-af: NPC MCAM and LDATA extract minimal configuration octeontx2-af: Enable packet length and csum validation octeontx2-af: Support for VTAG strip and capture ...
Diffstat (limited to 'tools/include/linux')
-rw-r--r--tools/include/linux/ring_buffer.h73
1 files changed, 73 insertions, 0 deletions
diff --git a/tools/include/linux/ring_buffer.h b/tools/include/linux/ring_buffer.h
new file mode 100644
index 000000000000..9a083ae60473
--- /dev/null
+++ b/tools/include/linux/ring_buffer.h
@@ -0,0 +1,73 @@
+#ifndef _TOOLS_LINUX_RING_BUFFER_H_
+#define _TOOLS_LINUX_RING_BUFFER_H_
+
+#include <asm/barrier.h>
+
+/*
+ * Contract with kernel for walking the perf ring buffer from
+ * user space requires the following barrier pairing (quote
+ * from kernel/events/ring_buffer.c):
+ *
+ * Since the mmap() consumer (userspace) can run on a
+ * different CPU:
+ *
+ * kernel user
+ *
+ * if (LOAD ->data_tail) { LOAD ->data_head
+ * (A) smp_rmb() (C)
+ * STORE $data LOAD $data
+ * smp_wmb() (B) smp_mb() (D)
+ * STORE ->data_head STORE ->data_tail
+ * }
+ *
+ * Where A pairs with D, and B pairs with C.
+ *
+ * In our case A is a control dependency that separates the
+ * load of the ->data_tail and the stores of $data. In case
+ * ->data_tail indicates there is no room in the buffer to
+ * store $data we do not.
+ *
+ * D needs to be a full barrier since it separates the data
+ * READ from the tail WRITE.
+ *
+ * For B a WMB is sufficient since it separates two WRITEs,
+ * and for C an RMB is sufficient since it separates two READs.
+ *
+ * Note, instead of B, C, D we could also use smp_store_release()
+ * in B and D as well as smp_load_acquire() in C.
+ *
+ * However, this optimization does not make sense for all kernel
+ * supported architectures since for a fair number it would
+ * resolve into READ_ONCE() + smp_mb() pair for smp_load_acquire(),
+ * and smp_mb() + WRITE_ONCE() pair for smp_store_release().
+ *
+ * Thus for those smp_wmb() in B and smp_rmb() in C would still
+ * be less expensive. For the case of D this has either the same
+ * cost or is less expensive, for example, due to TSO x86 can
+ * avoid the CPU barrier entirely.
+ */
+
+static inline u64 ring_buffer_read_head(struct perf_event_mmap_page *base)
+{
+/*
+ * Architectures where smp_load_acquire() does not fallback to
+ * READ_ONCE() + smp_mb() pair.
+ */
+#if defined(__x86_64__) || defined(__aarch64__) || defined(__powerpc64__) || \
+ defined(__ia64__) || defined(__sparc__) && defined(__arch64__)
+ return smp_load_acquire(&base->data_head);
+#else
+ u64 head = READ_ONCE(base->data_head);
+
+ smp_rmb();
+ return head;
+#endif
+}
+
+static inline void ring_buffer_write_tail(struct perf_event_mmap_page *base,
+ u64 tail)
+{
+ smp_store_release(&base->data_tail, tail);
+}
+
+#endif /* _TOOLS_LINUX_RING_BUFFER_H_ */