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net: shaper: drop redundant xa_lock() bracketing

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The shaper insertion and update code takes xa_lock() explicitly.
Paolo explained that the locking was purely to avoid re-taking
the lock in loops. But it may be mis-read as if it was expecting
readers to be fenced off by xa_lock. Readers of XArray are purely
under RCU. Remove explicit taking of xa_lock().

All writers to hierarchy->shapers are serialized by the netdev
instance lock (or run after netdev is made inaccessible to readers).

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Link: https://patch.msgid.link/20260609183224.1108521-2-kuba@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Jakub Kicinski 2026-06-09 11:32:21 -07:00 committed by Paolo Abeni
parent e6d6a68f1d
commit f26cddcf2a
1 changed files with 2 additions and 8 deletions
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10
net/shaper/shaper.c
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@ -429,7 +429,6 @@ static void net_shaper_commit(struct net_shaper_binding *binding,
int index;
int i;
xa_lock(&hierarchy->shapers);
for (i = 0; i < nr_shapers; ++i) {
index = net_shaper_handle_to_index(&shapers[i].handle);
@ -442,7 +441,6 @@ static void net_shaper_commit(struct net_shaper_binding *binding,
/* ... publish to lockless readers. */
smp_store_release(&cur->valid, true);
}
xa_unlock(&hierarchy->shapers);
}
/* Rollback all the tentative inserts from the hierarchy. */
@ -455,14 +453,12 @@ static void net_shaper_rollback(struct net_shaper_binding *binding)
if (!hierarchy)
return;
xa_lock(&hierarchy->shapers);
xa_for_each(&hierarchy->shapers, index, cur) {
if (cur->valid)
continue;
__xa_erase(&hierarchy->shapers, index);
xa_erase(&hierarchy->shapers, index);
kfree_rcu(cur, rcu);
}
xa_unlock(&hierarchy->shapers);
}
static int net_shaper_parse_handle(const struct nlattr *attr,
@ -1472,12 +1468,10 @@ static void net_shaper_flush(struct net_shaper_binding *binding)
if (!hierarchy)
return;
xa_lock(&hierarchy->shapers);
xa_for_each(&hierarchy->shapers, index, cur) {
__xa_erase(&hierarchy->shapers, index);
xa_erase(&hierarchy->shapers, index);
kfree(cur);
}
xa_unlock(&hierarchy->shapers);
kfree(hierarchy);
}