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From: Andrii Nakryiko <andriin@fb.com>
To: <bpf@vger.kernel.org>, <netdev@vger.kernel.org>, <ast@fb.com>,
	<daniel@iogearbox.net>, <dsahern@gmail.com>
Cc: <andrii.nakryiko@gmail.com>, <kernel-team@fb.com>,
	Andrii Nakryiko <andriin@fb.com>
Subject: [PATCH v4 bpf-next 3/9] bpf, xdp: extract common XDP program attachment logic
Date: Tue, 21 Jul 2020 23:45:56 -0700	[thread overview]
Message-ID: <20200722064603.3350758-4-andriin@fb.com> (raw)
In-Reply-To: <20200722064603.3350758-1-andriin@fb.com>

Further refactor XDP attachment code. dev_change_xdp_fd() is split into two
parts: getting bpf_progs from FDs and attachment logic, working with
bpf_progs. This makes attachment  logic a bit more straightforward and
prepares code for bpf_xdp_link inclusion, which will share the common logic.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
---
 net/core/dev.c | 165 +++++++++++++++++++++++++++----------------------
 1 file changed, 91 insertions(+), 74 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 7e753e248cef..abf573b2dcf4 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -8815,111 +8815,128 @@ static void dev_xdp_uninstall(struct net_device *dev)
 	}
 }
 
-/**
- *	dev_change_xdp_fd - set or clear a bpf program for a device rx path
- *	@dev: device
- *	@extack: netlink extended ack
- *	@fd: new program fd or negative value to clear
- *	@expected_fd: old program fd that userspace expects to replace or clear
- *	@flags: xdp-related flags
- *
- *	Set or clear a bpf program for a device
- */
-int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
-		      int fd, int expected_fd, u32 flags)
+static int dev_xdp_attach(struct net_device *dev, struct netlink_ext_ack *extack,
+			  struct bpf_prog *new_prog, struct bpf_prog *old_prog,
+			  u32 flags)
 {
-	const struct net_device_ops *ops = dev->netdev_ops;
-	enum bpf_xdp_mode mode = dev_xdp_mode(flags);
-	bool offload = mode == XDP_MODE_HW;
-	u32 prog_id, expected_id = 0;
-	struct bpf_prog *prog;
+	struct bpf_prog *cur_prog;
+	enum bpf_xdp_mode mode;
 	bpf_op_t bpf_op;
 	int err;
 
 	ASSERT_RTNL();
 
-	bpf_op = dev_xdp_bpf_op(dev, mode);
-	if (!bpf_op) {
-		NL_SET_ERR_MSG(extack, "underlying driver does not support XDP in native mode");
-		return -EOPNOTSUPP;
+	/* just one XDP mode bit should be set, zero defaults to SKB mode */
+	if (hweight32(flags & XDP_FLAGS_MODES) > 1) {
+		NL_SET_ERR_MSG(extack, "Only one XDP mode flag can be set");
+		return -EINVAL;
+	}
+	/* old_prog != NULL implies XDP_FLAGS_REPLACE is set */
+	if (old_prog && !(flags & XDP_FLAGS_REPLACE)) {
+		NL_SET_ERR_MSG(extack, "XDP_FLAGS_REPLACE is not specified");
+		return -EINVAL;
 	}
 
-	prog_id = dev_xdp_prog_id(dev, mode);
-	if (flags & XDP_FLAGS_REPLACE) {
-		if (expected_fd >= 0) {
-			prog = bpf_prog_get_type_dev(expected_fd,
-						     BPF_PROG_TYPE_XDP,
-						     bpf_op == ops->ndo_bpf);
-			if (IS_ERR(prog))
-				return PTR_ERR(prog);
-			expected_id = prog->aux->id;
-			bpf_prog_put(prog);
-		}
-
-		if (prog_id != expected_id) {
-			NL_SET_ERR_MSG(extack, "Active program does not match expected");
-			return -EEXIST;
-		}
+	mode = dev_xdp_mode(flags);
+	cur_prog = dev_xdp_prog(dev, mode);
+	if ((flags & XDP_FLAGS_REPLACE) && cur_prog != old_prog) {
+		NL_SET_ERR_MSG(extack, "Active program does not match expected");
+		return -EEXIST;
 	}
-	if (fd >= 0) {
+	if ((flags & XDP_FLAGS_UPDATE_IF_NOEXIST) && cur_prog) {
+		NL_SET_ERR_MSG(extack, "XDP program already attached");
+		return -EBUSY;
+	}
+
+	if (new_prog) {
+		bool offload = mode == XDP_MODE_HW;
 		enum bpf_xdp_mode other_mode = mode == XDP_MODE_SKB
 					       ? XDP_MODE_DRV : XDP_MODE_SKB;
 
-		if (!offload && dev_xdp_prog_id(dev, other_mode)) {
+		if (!offload && dev_xdp_prog(dev, other_mode)) {
 			NL_SET_ERR_MSG(extack, "Native and generic XDP can't be active at the same time");
 			return -EEXIST;
 		}
-
-		if ((flags & XDP_FLAGS_UPDATE_IF_NOEXIST) && prog_id) {
-			NL_SET_ERR_MSG(extack, "XDP program already attached");
-			return -EBUSY;
-		}
-
-		prog = bpf_prog_get_type_dev(fd, BPF_PROG_TYPE_XDP,
-					     bpf_op == ops->ndo_bpf);
-		if (IS_ERR(prog))
-			return PTR_ERR(prog);
-
-		if (!offload && bpf_prog_is_dev_bound(prog->aux)) {
+		if (!offload && bpf_prog_is_dev_bound(new_prog->aux)) {
 			NL_SET_ERR_MSG(extack, "Using device-bound program without HW_MODE flag is not supported");
-			bpf_prog_put(prog);
 			return -EINVAL;
 		}
-
-		if (prog->expected_attach_type == BPF_XDP_DEVMAP) {
+		if (new_prog->expected_attach_type == BPF_XDP_DEVMAP) {
 			NL_SET_ERR_MSG(extack, "BPF_XDP_DEVMAP programs can not be attached to a device");
-			bpf_prog_put(prog);
 			return -EINVAL;
 		}
-
-		if (prog->expected_attach_type == BPF_XDP_CPUMAP) {
-			NL_SET_ERR_MSG(extack,
-				       "BPF_XDP_CPUMAP programs can not be attached to a device");
-			bpf_prog_put(prog);
+		if (new_prog->expected_attach_type == BPF_XDP_CPUMAP) {
+			NL_SET_ERR_MSG(extack, "BPF_XDP_CPUMAP programs can not be attached to a device");
 			return -EINVAL;
 		}
+	}
 
-		/* prog->aux->id may be 0 for orphaned device-bound progs */
-		if (prog->aux->id && prog->aux->id == prog_id) {
-			bpf_prog_put(prog);
-			return 0;
+	/* don't call drivers if the effective program didn't change */
+	if (new_prog != cur_prog) {
+		bpf_op = dev_xdp_bpf_op(dev, mode);
+		if (!bpf_op) {
+			NL_SET_ERR_MSG(extack, "Underlying driver does not support XDP in native mode");
+			return -EOPNOTSUPP;
 		}
-	} else {
-		if (!prog_id)
-			return 0;
-		prog = NULL;
-	}
 
-	err = dev_xdp_install(dev, mode, bpf_op, extack, flags, prog);
-	if (err < 0 && prog) {
-		bpf_prog_put(prog);
-		return err;
+		err = dev_xdp_install(dev, mode, bpf_op, extack, flags, new_prog);
+		if (err)
+			return err;
 	}
-	dev_xdp_set_prog(dev, mode, prog);
+
+	dev_xdp_set_prog(dev, mode, new_prog);
+	if (cur_prog)
+		bpf_prog_put(cur_prog);
 
 	return 0;
 }
 
+/**
+ *	dev_change_xdp_fd - set or clear a bpf program for a device rx path
+ *	@dev: device
+ *	@extack: netlink extended ack
+ *	@fd: new program fd or negative value to clear
+ *	@expected_fd: old program fd that userspace expects to replace or clear
+ *	@flags: xdp-related flags
+ *
+ *	Set or clear a bpf program for a device
+ */
+int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
+		      int fd, int expected_fd, u32 flags)
+{
+	enum bpf_xdp_mode mode = dev_xdp_mode(flags);
+	struct bpf_prog *new_prog = NULL, *old_prog = NULL;
+	int err;
+
+	ASSERT_RTNL();
+
+	if (fd >= 0) {
+		new_prog = bpf_prog_get_type_dev(fd, BPF_PROG_TYPE_XDP,
+						 mode != XDP_MODE_SKB);
+		if (IS_ERR(new_prog))
+			return PTR_ERR(new_prog);
+	}
+
+	if (expected_fd >= 0) {
+		old_prog = bpf_prog_get_type_dev(expected_fd, BPF_PROG_TYPE_XDP,
+						 mode != XDP_MODE_SKB);
+		if (IS_ERR(old_prog)) {
+			err = PTR_ERR(old_prog);
+			old_prog = NULL;
+			goto err_out;
+		}
+	}
+
+	err = dev_xdp_attach(dev, extack, new_prog, old_prog, flags);
+
+err_out:
+	if (err && new_prog)
+		bpf_prog_put(new_prog);
+	if (old_prog)
+		bpf_prog_put(old_prog);
+	return err;
+}
+
 /**
  *	dev_new_index	-	allocate an ifindex
  *	@net: the applicable net namespace
-- 
2.24.1


  parent reply	other threads:[~2020-07-22  6:46 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-22  6:45 [PATCH v4 bpf-next 0/9] BPF XDP link Andrii Nakryiko
2020-07-22  6:45 ` [PATCH v4 bpf-next 1/9] bpf: make bpf_link API available indepently of CONFIG_BPF_SYSCALL Andrii Nakryiko
2020-07-22  6:45 ` [PATCH v4 bpf-next 2/9] bpf, xdp: maintain info on attached XDP BPF programs in net_device Andrii Nakryiko
2020-07-22 15:26   ` Maciej Fijalkowski
2020-07-22 19:35     ` Andrii Nakryiko
2020-07-22 19:56       ` Maciej Fijalkowski
2020-07-22  6:45 ` Andrii Nakryiko [this message]
2020-07-22 19:13   ` [PATCH v4 bpf-next 3/9] bpf, xdp: extract common XDP program attachment logic Maciej Fijalkowski
2020-07-22 19:29     ` Andrii Nakryiko
2020-07-27 12:07   ` Shay Agroskin
2020-07-27 18:51     ` Andrii Nakryiko
2020-08-11 18:14   ` sdf
2020-08-12  2:19     ` Andrii Nakryiko
2020-07-22  6:45 ` [PATCH v4 bpf-next 4/9] bpf, xdp: add bpf_link-based XDP attachment API Andrii Nakryiko
2020-07-22  6:45 ` [PATCH v4 bpf-next 5/9] bpf, xdp: implement LINK_UPDATE for BPF XDP link Andrii Nakryiko
2020-07-22  6:45 ` [PATCH v4 bpf-next 6/9] bpf: implement BPF XDP link-specific introspection APIs Andrii Nakryiko
2020-07-22  6:46 ` [PATCH v4 bpf-next 7/9] libbpf: add support for BPF XDP link Andrii Nakryiko
2020-07-22  6:46 ` [PATCH v4 bpf-next 8/9] selftests/bpf: add BPF XDP link selftests Andrii Nakryiko
2020-07-22  6:46 ` [PATCH v4 bpf-next 9/9] bpf, xdp: remove XDP_QUERY_PROG and XDP_QUERY_PROG_HW XDP commands Andrii Nakryiko
2020-07-26  3:46 ` [PATCH v4 bpf-next 0/9] BPF XDP link Alexei Starovoitov

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