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>

1 files changed, 11 insertions, 7 deletions

diff --git a/net/sched/sch_gred.c b/net/sched/sch_gred.c
index 1b5e63126cb3..53204de71c39 100644
--- 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;
 }