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Message-Id: <20201106180741.2839668-2-tannerlove.kernel@gmail.com>
Date: Fri, 6 Nov 2020 13:07:40 -0500
From: Tanner Love <tannerlove.kernel@...il.com>
To: netdev@...r.kernel.org
Cc: davem@...emloft.net, Tanner Love <tannerlove@...gle.com>,
Willem de Bruijn <willemb@...gle.com>,
Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next 1/2] net/packet: make packet_fanout.arr size configurable up to 64K
From: Tanner Love <tannerlove@...gle.com>
One use case of PACKET_FANOUT is lockless reception with one socket
per CPU. 256 is a practical limit on increasingly many machines.
Increase PACKET_FANOUT_MAX to 64K. Expand setsockopt PACKET_FANOUT to
take an extra argument max_num_members. Also explicitly define a
fanout_args struct, instead of implicitly casting to an integer. This
documents the API and simplifies the control flow.
If max_num_members is not specified or is set to 0, then 256 is used,
same as before.
Signed-off-by: Tanner Love <tannerlove@...gle.com>
Signed-off-by: Willem de Bruijn <willemb@...gle.com>
Reviewed-by: Eric Dumazet <edumazet@...gle.com>
---
include/uapi/linux/if_packet.h | 12 +++++++++++
net/packet/af_packet.c | 37 +++++++++++++++++++++++-----------
net/packet/internal.h | 5 +++--
3 files changed, 40 insertions(+), 14 deletions(-)
diff --git a/include/uapi/linux/if_packet.h b/include/uapi/linux/if_packet.h
index 3d884d68eb30..c07caf7b40db 100644
--- a/include/uapi/linux/if_packet.h
+++ b/include/uapi/linux/if_packet.h
@@ -2,6 +2,7 @@
#ifndef __LINUX_IF_PACKET_H
#define __LINUX_IF_PACKET_H
+#include <asm/byteorder.h>
#include <linux/types.h>
struct sockaddr_pkt {
@@ -296,6 +297,17 @@ struct packet_mreq {
unsigned char mr_address[8];
};
+struct fanout_args {
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+ __u16 id;
+ __u16 type_flags;
+#else
+ __u16 type_flags;
+ __u16 id;
+#endif
+ __u32 max_num_members;
+};
+
#define PACKET_MR_MULTICAST 0
#define PACKET_MR_PROMISC 1
#define PACKET_MR_ALLMULTI 2
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index cefbd50c1090..62ebfaa7adcb 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1636,13 +1636,15 @@ static bool fanout_find_new_id(struct sock *sk, u16 *new_id)
return false;
}
-static int fanout_add(struct sock *sk, u16 id, u16 type_flags)
+static int fanout_add(struct sock *sk, struct fanout_args *args)
{
struct packet_rollover *rollover = NULL;
struct packet_sock *po = pkt_sk(sk);
+ u16 type_flags = args->type_flags;
struct packet_fanout *f, *match;
u8 type = type_flags & 0xff;
u8 flags = type_flags >> 8;
+ u16 id = args->id;
int err;
switch (type) {
@@ -1700,11 +1702,21 @@ static int fanout_add(struct sock *sk, u16 id, u16 type_flags)
}
}
err = -EINVAL;
- if (match && match->flags != flags)
- goto out;
- if (!match) {
+ if (match) {
+ if (match->flags != flags)
+ goto out;
+ if (args->max_num_members &&
+ args->max_num_members != match->max_num_members)
+ goto out;
+ } else {
+ if (args->max_num_members > PACKET_FANOUT_MAX)
+ goto out;
+ if (!args->max_num_members)
+ /* legacy PACKET_FANOUT_MAX */
+ args->max_num_members = 256;
err = -ENOMEM;
- match = kzalloc(sizeof(*match), GFP_KERNEL);
+ match = kvzalloc(struct_size(match, arr, args->max_num_members),
+ GFP_KERNEL);
if (!match)
goto out;
write_pnet(&match->net, sock_net(sk));
@@ -1720,6 +1732,7 @@ static int fanout_add(struct sock *sk, u16 id, u16 type_flags)
match->prot_hook.func = packet_rcv_fanout;
match->prot_hook.af_packet_priv = match;
match->prot_hook.id_match = match_fanout_group;
+ match->max_num_members = args->max_num_members;
list_add(&match->list, &fanout_list);
}
err = -EINVAL;
@@ -1730,7 +1743,7 @@ static int fanout_add(struct sock *sk, u16 id, u16 type_flags)
match->prot_hook.type == po->prot_hook.type &&
match->prot_hook.dev == po->prot_hook.dev) {
err = -ENOSPC;
- if (refcount_read(&match->sk_ref) < PACKET_FANOUT_MAX) {
+ if (refcount_read(&match->sk_ref) < match->max_num_members) {
__dev_remove_pack(&po->prot_hook);
po->fanout = match;
po->rollover = rollover;
@@ -1744,7 +1757,7 @@ static int fanout_add(struct sock *sk, u16 id, u16 type_flags)
if (err && !refcount_read(&match->sk_ref)) {
list_del(&match->list);
- kfree(match);
+ kvfree(match);
}
out:
@@ -3075,7 +3088,7 @@ static int packet_release(struct socket *sock)
kfree(po->rollover);
if (f) {
fanout_release_data(f);
- kfree(f);
+ kvfree(f);
}
/*
* Now the socket is dead. No more input will appear.
@@ -3866,14 +3879,14 @@ packet_setsockopt(struct socket *sock, int level, int optname, sockptr_t optval,
}
case PACKET_FANOUT:
{
- int val;
+ struct fanout_args args = { 0 };
- if (optlen != sizeof(val))
+ if (optlen != sizeof(int) && optlen != sizeof(args))
return -EINVAL;
- if (copy_from_sockptr(&val, optval, sizeof(val)))
+ if (copy_from_sockptr(&args, optval, optlen))
return -EFAULT;
- return fanout_add(sk, val & 0xffff, val >> 16);
+ return fanout_add(sk, &args);
}
case PACKET_FANOUT_DATA:
{
diff --git a/net/packet/internal.h b/net/packet/internal.h
index fd41ecb7f605..baafc3f3fa25 100644
--- a/net/packet/internal.h
+++ b/net/packet/internal.h
@@ -77,11 +77,12 @@ struct packet_ring_buffer {
};
extern struct mutex fanout_mutex;
-#define PACKET_FANOUT_MAX 256
+#define PACKET_FANOUT_MAX (1 << 16)
struct packet_fanout {
possible_net_t net;
unsigned int num_members;
+ u32 max_num_members;
u16 id;
u8 type;
u8 flags;
@@ -90,10 +91,10 @@ struct packet_fanout {
struct bpf_prog __rcu *bpf_prog;
};
struct list_head list;
- struct sock *arr[PACKET_FANOUT_MAX];
spinlock_t lock;
refcount_t sk_ref;
struct packet_type prot_hook ____cacheline_aligned_in_smp;
+ struct sock *arr[];
};
struct packet_rollover {
--
2.29.1.341.ge80a0c044ae-goog
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