sch_gred: prefer GFP_KERNEL allocations

In control path, its better to use GFP_KERNEL allocations where
possible.

Before taking qdisc spinlock, we preallocate memory just in case we'll
need it in gred_change_vq()

This is a followup to commit 3f1e6d3fd37b (sch_gred: should not use
GFP_KERNEL while holding a spinlock)

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/sched/sch_gred.c b/net/sched/sch_gred.c
index 1b5e631..53204de 100644 (file)
--- a/net/sched/sch_gred.c
+++ b/net/sched/sch_gred.c
@@ -380,18 +380,19 @@ static inline int gred_change_table_def(struct Qdisc *sch, struct nlattr *dps)
 
 static inline int gred_change_vq(struct Qdisc *sch, int dp,
                                 struct tc_gred_qopt *ctl, int prio,
-                                u8 *stab, u32 max_P)
+                                u8 *stab, u32 max_P,
+                                struct gred_sched_data **prealloc)
 {
        struct gred_sched *table = qdisc_priv(sch);
-       struct gred_sched_data *q;
+       struct gred_sched_data *q = table->tab[dp];
 
-       if (table->tab[dp] == NULL) {
-               table->tab[dp] = kzalloc(sizeof(*q), GFP_ATOMIC);
-               if (table->tab[dp] == NULL)
+       if (!q) {
+               table->tab[dp] = q = *prealloc;
+               *prealloc = NULL;
+               if (!q)
                        return -ENOMEM;
        }
 
-       q = table->tab[dp];
        q->DP = dp;
        q->prio = prio;
        q->limit = ctl->limit;
@@ -421,6 +422,7 @@ static int gred_change(struct Qdisc *sch, struct nlattr *opt)
        int err, prio = GRED_DEF_PRIO;
        u8 *stab;
        u32 max_P;
+       struct gred_sched_data *prealloc;
 
        if (opt == NULL)
                return -EINVAL;
@@ -460,9 +462,10 @@ static int gred_change(struct Qdisc *sch, struct nlattr *opt)
                        prio = ctl->prio;
        }
 
+       prealloc = kzalloc(sizeof(*prealloc), GFP_KERNEL);
        sch_tree_lock(sch);
 
-       err = gred_change_vq(sch, ctl->DP, ctl, prio, stab, max_P);
+       err = gred_change_vq(sch, ctl->DP, ctl, prio, stab, max_P, &prealloc);
        if (err < 0)
                goto errout_locked;
 
@@ -476,6 +479,7 @@ static int gred_change(struct Qdisc *sch, struct nlattr *opt)
 
 errout_locked:
        sch_tree_unlock(sch);
+       kfree(prealloc);
 errout:
        return err;
 }