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authorLinus Torvalds <torvalds@linux-foundation.org>2021-12-09 22:26:44 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2021-12-09 22:26:44 +0300
commitded746bfc94398d2ee9de315a187677b207b2004 (patch)
tree30d2516b57e391a573aa4f98ad9039095a2ab2b7 /Documentation
parent27698cd2a3c07d124fad6bfc8dd93fd1c5d46879 (diff)
parent04ec4e6250e5f58b525b08f3dca45c7d7427620e (diff)
downloadlinux-ded746bfc94398d2ee9de315a187677b207b2004.tar.xz
Merge tag 'net-5.16-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Pull networking fixes from Jakub Kicinski: "Including fixes from bpf, can and netfilter. Current release - regressions: - bpf, sockmap: re-evaluate proto ops when psock is removed from sockmap Current release - new code bugs: - bpf: fix bpf_check_mod_kfunc_call for built-in modules - ice: fixes for TC classifier offloads - vrf: don't run conntrack on vrf with !dflt qdisc Previous releases - regressions: - bpf: fix the off-by-two error in range markings - seg6: fix the iif in the IPv6 socket control block - devlink: fix netns refcount leak in devlink_nl_cmd_reload() - dsa: mv88e6xxx: fix "don't use PHY_DETECT on internal PHY's" - dsa: mv88e6xxx: allow use of PHYs on CPU and DSA ports Previous releases - always broken: - ethtool: do not perform operations on net devices being unregistered - udp: use datalen to cap max gso segments - ice: fix races in stats collection - fec: only clear interrupt of handling queue in fec_enet_rx_queue() - m_can: pci: fix incorrect reference clock rate - m_can: disable and ignore ELO interrupt - mvpp2: fix XDP rx queues registering Misc: - treewide: add missing includes masked by cgroup -> bpf.h dependency" * tag 'net-5.16-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (82 commits) net: dsa: mv88e6xxx: allow use of PHYs on CPU and DSA ports net: wwan: iosm: fixes unable to send AT command during mbim tx net: wwan: iosm: fixes net interface nonfunctional after fw flash net: wwan: iosm: fixes unnecessary doorbell send net: dsa: felix: Fix memory leak in felix_setup_mmio_filtering MAINTAINERS: s390/net: remove myself as maintainer net/sched: fq_pie: prevent dismantle issue net: mana: Fix memory leak in mana_hwc_create_wq seg6: fix the iif in the IPv6 socket control block nfp: Fix memory leak in nfp_cpp_area_cache_add() nfc: fix potential NULL pointer deref in nfc_genl_dump_ses_done nfc: fix segfault in nfc_genl_dump_devices_done udp: using datalen to cap max gso segments net: dsa: mv88e6xxx: error handling for serdes_power functions can: kvaser_usb: get CAN clock frequency from device can: kvaser_pciefd: kvaser_pciefd_rx_error_frame(): increase correct stats->{rx,tx}_errors counter net: mvpp2: fix XDP rx queues registering vmxnet3: fix minimum vectors alloc issue net, neigh: clear whole pneigh_entry at alloc time net: dsa: mv88e6xxx: fix "don't use PHY_DETECT on internal PHY's" ...
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/locking/locktypes.rst9
1 files changed, 3 insertions, 6 deletions
diff --git a/Documentation/locking/locktypes.rst b/Documentation/locking/locktypes.rst
index ddada4a53749..4fd7b70fcde1 100644
--- a/Documentation/locking/locktypes.rst
+++ b/Documentation/locking/locktypes.rst
@@ -439,11 +439,9 @@ preemption. The following substitution works on both kernels::
spin_lock(&p->lock);
p->count += this_cpu_read(var2);
-On a non-PREEMPT_RT kernel migrate_disable() maps to preempt_disable()
-which makes the above code fully equivalent. On a PREEMPT_RT kernel
migrate_disable() ensures that the task is pinned on the current CPU which
in turn guarantees that the per-CPU access to var1 and var2 are staying on
-the same CPU.
+the same CPU while the task remains preemptible.
The migrate_disable() substitution is not valid for the following
scenario::
@@ -456,9 +454,8 @@ scenario::
p = this_cpu_ptr(&var1);
p->val = func2();
-While correct on a non-PREEMPT_RT kernel, this breaks on PREEMPT_RT because
-here migrate_disable() does not protect against reentrancy from a
-preempting task. A correct substitution for this case is::
+This breaks because migrate_disable() does not protect against reentrancy from
+a preempting task. A correct substitution for this case is::
func()
{