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| author | Paul E. McKenney <paulmck@kernel.org> | 2022-01-20 13:39:33 -0800 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2022-04-11 15:31:02 -0700 |
| commit | 7b9e9b5856e188c1b3ff51185f3600ee79b4ab41 (patch) | |
| tree | 793309999e33b3c5f439e55ecc18cbe741602b71 /kernel/rcu | |
| parent | 95ebe80d99de3cb849c522a1f768e5e8befa0b7c (diff) | |
| download | linux-stable-7b9e9b5856e188c1b3ff51185f3600ee79b4ab41.tar.gz linux-stable-7b9e9b5856e188c1b3ff51185f3600ee79b4ab41.tar.bz2 linux-stable-7b9e9b5856e188c1b3ff51185f3600ee79b4ab41.zip | |
srcu: Make srcu_funnel_gp_start() cache ->mynode in snp_leaf
Currently, the srcu_funnel_gp_start() walks its local variable snp up the
tree and reloads sdp->mynode whenever it is necessary to check whether
it is still at the leaf srcu_node level. This works, but is a bit more
obtuse than absolutely necessary. In addition, upcoming commits will
dynamically size srcu_struct structures, in which case sdp->mynode will
no longer necessarily be a constant, and this commit helps prepare for
that dynamic sizing.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/srcutree.c | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index d30e4db04506..7d13e35e5d27 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -632,20 +632,21 @@ static void srcu_funnel_gp_start(struct srcu_struct *ssp, struct srcu_data *sdp, { unsigned long flags; int idx = rcu_seq_ctr(s) % ARRAY_SIZE(sdp->mynode->srcu_have_cbs); - struct srcu_node *snp = sdp->mynode; + struct srcu_node *snp; + struct srcu_node *snp_leaf = sdp->mynode; unsigned long snp_seq; /* Each pass through the loop does one level of the srcu_node tree. */ - for (; snp != NULL; snp = snp->srcu_parent) { - if (rcu_seq_done(&ssp->srcu_gp_seq, s) && snp != sdp->mynode) + for (snp = snp_leaf; snp != NULL; snp = snp->srcu_parent) { + if (rcu_seq_done(&ssp->srcu_gp_seq, s) && snp != snp_leaf) return; /* GP already done and CBs recorded. */ spin_lock_irqsave_rcu_node(snp, flags); if (ULONG_CMP_GE(snp->srcu_have_cbs[idx], s)) { snp_seq = snp->srcu_have_cbs[idx]; - if (snp == sdp->mynode && snp_seq == s) + if (snp == snp_leaf && snp_seq == s) snp->srcu_data_have_cbs[idx] |= sdp->grpmask; spin_unlock_irqrestore_rcu_node(snp, flags); - if (snp == sdp->mynode && snp_seq != s) { + if (snp == snp_leaf && snp_seq != s) { srcu_schedule_cbs_sdp(sdp, do_norm ? SRCU_INTERVAL : 0); @@ -656,7 +657,7 @@ static void srcu_funnel_gp_start(struct srcu_struct *ssp, struct srcu_data *sdp, return; } snp->srcu_have_cbs[idx] = s; - if (snp == sdp->mynode) + if (snp == snp_leaf) snp->srcu_data_have_cbs[idx] |= sdp->grpmask; if (!do_norm && ULONG_CMP_LT(snp->srcu_gp_seq_needed_exp, s)) WRITE_ONCE(snp->srcu_gp_seq_needed_exp, s); |