From dcfea72e79b0aa7a057c8f6024169d86a1bbc84b Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Wed, 8 Jan 2020 16:59:02 -0500 Subject: net: introduce skb_list_walk_safe for skb segment walking As part of the continual effort to remove direct usage of skb->next and skb->prev, this patch adds a helper for iterating through the singly-linked variant of skb lists, which are used for lists of GSO packet. The name "skb_list_..." has been chosen to match the existing function, "kfree_skb_list, which also operates on these singly-linked lists, and the "..._walk_safe" part is the same idiom as elsewhere in the kernel. This patch removes the helper from wireguard and puts it into linux/skbuff.h, while making it a bit more robust for general usage. In particular, parenthesis are added around the macro argument usage, and it now accounts for trying to iterate through an already-null skb pointer, which will simply run the iteration zero times. This latter enhancement means it can be used to replace both do { ... } while and while (...) open-coded idioms. This should take care of these three possible usages, which match all current methods of iterations. skb_list_walk_safe(segs, skb, next) { ... } skb_list_walk_safe(skb, skb, next) { ... } skb_list_walk_safe(segs, skb, segs) { ... } Gcc appears to generate efficient code for each of these. Signed-off-by: Jason A. Donenfeld Signed-off-by: David S. Miller --- drivers/net/wireguard/device.h | 8 -------- include/linux/skbuff.h | 5 +++++ 2 files changed, 5 insertions(+), 8 deletions(-) diff --git a/drivers/net/wireguard/device.h b/drivers/net/wireguard/device.h index c91f3051c5c7..b15a8be9d816 100644 --- a/drivers/net/wireguard/device.h +++ b/drivers/net/wireguard/device.h @@ -62,12 +62,4 @@ struct wg_device { int wg_device_init(void); void wg_device_uninit(void); -/* Later after the dust settles, this can be moved into include/linux/skbuff.h, - * where virtually all code that deals with GSO segs can benefit, around ~30 - * drivers as of writing. - */ -#define skb_list_walk_safe(first, skb, next) \ - for (skb = first, next = skb->next; skb; \ - skb = next, next = skb ? skb->next : NULL) - #endif /* _WG_DEVICE_H */ diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index e9133bcf0544..64e5b1be9ff5 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -1478,6 +1478,11 @@ static inline void skb_mark_not_on_list(struct sk_buff *skb) skb->next = NULL; } +/* Iterate through singly-linked GSO fragments of an skb. */ +#define skb_list_walk_safe(first, skb, next) \ + for ((skb) = (first), (next) = (skb) ? (skb)->next : NULL; (skb); \ + (skb) = (next), (next) = (skb) ? (skb)->next : NULL) + static inline void skb_list_del_init(struct sk_buff *skb) { __list_del_entry(&skb->list); -- cgit v1.2.3-59-g8ed1b From 5643a552d31242e5adf3dbefba26c90b1bce2826 Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Wed, 8 Jan 2020 16:59:03 -0500 Subject: net: tap: use skb_list_walk_safe helper for gso segments This is a straight-forward conversion case for the new function, and while we're at it, we can remove a null write to skb->next by replacing it with skb_mark_not_on_list. Signed-off-by: Jason A. Donenfeld Signed-off-by: David S. Miller --- drivers/net/tap.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) diff --git a/drivers/net/tap.c b/drivers/net/tap.c index a6d63665ad03..1f4bdd94407a 100644 --- a/drivers/net/tap.c +++ b/drivers/net/tap.c @@ -341,6 +341,7 @@ rx_handler_result_t tap_handle_frame(struct sk_buff **pskb) features |= tap->tap_features; if (netif_needs_gso(skb, features)) { struct sk_buff *segs = __skb_gso_segment(skb, features, false); + struct sk_buff *next; if (IS_ERR(segs)) goto drop; @@ -352,16 +353,13 @@ rx_handler_result_t tap_handle_frame(struct sk_buff **pskb) } consume_skb(skb); - while (segs) { - struct sk_buff *nskb = segs->next; - - segs->next = NULL; - if (ptr_ring_produce(&q->ring, segs)) { - kfree_skb(segs); - kfree_skb_list(nskb); + skb_list_walk_safe(segs, skb, next) { + skb_mark_not_on_list(skb); + if (ptr_ring_produce(&q->ring, skb)) { + kfree_skb(skb); + kfree_skb_list(next); break; } - segs = nskb; } } else { /* If we receive a partial checksum and the tap side -- cgit v1.2.3-59-g8ed1b From 1d7a7438d78f2da56b6b3855be462cf0fc809e56 Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Wed, 8 Jan 2020 16:59:04 -0500 Subject: net: r8152: use skb_list_walk_safe helper for gso segments This is a straight-forward conversion case for the new function, and while we're at it, we can remove a null write to skb->next by replacing it with skb_mark_not_on_list. Signed-off-by: Jason A. Donenfeld Signed-off-by: David S. Miller --- drivers/net/usb/r8152.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c index 9ec1da429514..fe22a582373b 100644 --- a/drivers/net/usb/r8152.c +++ b/drivers/net/usb/r8152.c @@ -1897,8 +1897,8 @@ static void r8152_csum_workaround(struct r8152 *tp, struct sk_buff *skb, { if (skb_shinfo(skb)->gso_size) { netdev_features_t features = tp->netdev->features; + struct sk_buff *segs, *seg, *next; struct sk_buff_head seg_list; - struct sk_buff *segs, *nskb; features &= ~(NETIF_F_SG | NETIF_F_IPV6_CSUM | NETIF_F_TSO6); segs = skb_gso_segment(skb, features); @@ -1907,12 +1907,10 @@ static void r8152_csum_workaround(struct r8152 *tp, struct sk_buff *skb, __skb_queue_head_init(&seg_list); - do { - nskb = segs; - segs = segs->next; - nskb->next = NULL; - __skb_queue_tail(&seg_list, nskb); - } while (segs); + skb_list_walk_safe(segs, seg, next) { + skb_mark_not_on_list(seg); + __skb_queue_tail(&seg_list, seg); + } skb_queue_splice(&seg_list, list); dev_kfree_skb(skb); -- cgit v1.2.3-59-g8ed1b From 9f0722380f75a0873c9d70286df8354c6895f983 Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Wed, 8 Jan 2020 16:59:05 -0500 Subject: net: tg3: use skb_list_walk_safe helper for gso segments This is a straight-forward conversion case for the new function, and while we're at it, we can remove a null write to skb->next by replacing it with skb_mark_not_on_list. Signed-off-by: Jason A. Donenfeld Signed-off-by: David S. Miller --- drivers/net/ethernet/broadcom/tg3.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/drivers/net/ethernet/broadcom/tg3.c b/drivers/net/ethernet/broadcom/tg3.c index 460b4992914a..88466255bf66 100644 --- a/drivers/net/ethernet/broadcom/tg3.c +++ b/drivers/net/ethernet/broadcom/tg3.c @@ -7874,8 +7874,8 @@ static netdev_tx_t tg3_start_xmit(struct sk_buff *, struct net_device *); static int tg3_tso_bug(struct tg3 *tp, struct tg3_napi *tnapi, struct netdev_queue *txq, struct sk_buff *skb) { - struct sk_buff *segs, *nskb; u32 frag_cnt_est = skb_shinfo(skb)->gso_segs * 3; + struct sk_buff *segs, *seg, *next; /* Estimate the number of fragments in the worst case */ if (unlikely(tg3_tx_avail(tnapi) <= frag_cnt_est)) { @@ -7898,12 +7898,10 @@ static int tg3_tso_bug(struct tg3 *tp, struct tg3_napi *tnapi, if (IS_ERR(segs) || !segs) goto tg3_tso_bug_end; - do { - nskb = segs; - segs = segs->next; - nskb->next = NULL; - tg3_start_xmit(nskb, tp->dev); - } while (segs); + skb_list_walk_safe(segs, seg, next) { + skb_mark_not_on_list(seg); + tg3_start_xmit(seg, tp->dev); + } tg3_tso_bug_end: dev_consume_skb_any(skb); -- cgit v1.2.3-59-g8ed1b From 90919f14507b7a3661e58b8d17f8444a63f5cafa Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Wed, 8 Jan 2020 16:59:06 -0500 Subject: net: sunvnet: use skb_list_walk_safe helper for gso segments This is a straight-forward conversion case for the new function, and while we're at it, we can remove a null write to skb->next by replacing it with skb_mark_not_on_list. Signed-off-by: Jason A. Donenfeld Signed-off-by: David S. Miller --- drivers/net/ethernet/sun/sunvnet_common.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) diff --git a/drivers/net/ethernet/sun/sunvnet_common.c b/drivers/net/ethernet/sun/sunvnet_common.c index a601a306f9a5..c23ce838ff63 100644 --- a/drivers/net/ethernet/sun/sunvnet_common.c +++ b/drivers/net/ethernet/sun/sunvnet_common.c @@ -1223,7 +1223,7 @@ vnet_handle_offloads(struct vnet_port *port, struct sk_buff *skb, { struct net_device *dev = VNET_PORT_TO_NET_DEVICE(port); struct vio_dring_state *dr = &port->vio.drings[VIO_DRIVER_TX_RING]; - struct sk_buff *segs; + struct sk_buff *segs, *curr, *next; int maclen, datalen; int status; int gso_size, gso_type, gso_segs; @@ -1282,11 +1282,8 @@ vnet_handle_offloads(struct vnet_port *port, struct sk_buff *skb, skb_reset_mac_header(skb); status = 0; - while (segs) { - struct sk_buff *curr = segs; - - segs = segs->next; - curr->next = NULL; + skb_list_walk_safe(segs, curr, next) { + skb_mark_not_on_list(curr); if (port->tso && curr->len > dev->mtu) { skb_shinfo(curr)->gso_size = gso_size; skb_shinfo(curr)->gso_type = gso_type; -- cgit v1.2.3-59-g8ed1b From 69b4ed5cbff54b8279f53a65da111e8d0cc01405 Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Wed, 8 Jan 2020 16:59:07 -0500 Subject: net: sfc: use skb_list_walk_safe helper for gso segments This is a straight-forward conversion case for the new function, and while we're at it, we can remove a null write to skb->next by replacing it with skb_mark_not_on_list. Signed-off-by: Jason A. Donenfeld Signed-off-by: David S. Miller --- drivers/net/ethernet/sfc/tx.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/drivers/net/ethernet/sfc/tx.c b/drivers/net/ethernet/sfc/tx.c index c9599fcab0b4..e4f0f5c94589 100644 --- a/drivers/net/ethernet/sfc/tx.c +++ b/drivers/net/ethernet/sfc/tx.c @@ -307,12 +307,9 @@ static int efx_tx_tso_fallback(struct efx_tx_queue *tx_queue, dev_consume_skb_any(skb); skb = segments; - while (skb) { - next = skb->next; - skb->next = NULL; - + skb_list_walk_safe(skb, skb, next) { + skb_mark_not_on_list(skb); efx_enqueue_skb(tx_queue, skb); - skb = next; } return 0; -- cgit v1.2.3-59-g8ed1b From 536577f36ff7afd0a0aff4ebef62db8afe6fc904 Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Wed, 8 Jan 2020 16:59:08 -0500 Subject: net: myri10ge: use skb_list_walk_safe helper for gso segments This is a straight-forward conversion case for the new function, and while we're at it, we can remove a null write to skb->next by replacing it with skb_mark_not_on_list. Signed-off-by: Jason A. Donenfeld Signed-off-by: David S. Miller --- drivers/net/ethernet/myricom/myri10ge/myri10ge.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/drivers/net/ethernet/myricom/myri10ge/myri10ge.c b/drivers/net/ethernet/myricom/myri10ge/myri10ge.c index c979f38a2e0c..2ee0d0be113a 100644 --- a/drivers/net/ethernet/myricom/myri10ge/myri10ge.c +++ b/drivers/net/ethernet/myricom/myri10ge/myri10ge.c @@ -2892,7 +2892,7 @@ drop: static netdev_tx_t myri10ge_sw_tso(struct sk_buff *skb, struct net_device *dev) { - struct sk_buff *segs, *curr; + struct sk_buff *segs, *curr, *next; struct myri10ge_priv *mgp = netdev_priv(dev); struct myri10ge_slice_state *ss; netdev_tx_t status; @@ -2901,10 +2901,8 @@ static netdev_tx_t myri10ge_sw_tso(struct sk_buff *skb, if (IS_ERR(segs)) goto drop; - while (segs) { - curr = segs; - segs = segs->next; - curr->next = NULL; + skb_list_walk_safe(segs, curr, next) { + skb_mark_not_on_list(curr); status = myri10ge_xmit(curr, dev); if (status != 0) { dev_kfree_skb_any(curr); -- cgit v1.2.3-59-g8ed1b From 66de4b179f163ea106f292778563b404958e4f42 Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Wed, 8 Jan 2020 16:59:09 -0500 Subject: net: iwlwifi: use skb_list_walk_safe helper for gso segments This is a straight-forward conversion case for the new function, and while we're at it, we can remove a null write to skb->next by replacing it with skb_mark_not_on_list. Signed-off-by: Jason A. Donenfeld Signed-off-by: David S. Miller --- drivers/net/wireless/intel/iwlwifi/mvm/tx.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/tx.c b/drivers/net/wireless/intel/iwlwifi/mvm/tx.c index dc5c02fbc65a..6a241d37a057 100644 --- a/drivers/net/wireless/intel/iwlwifi/mvm/tx.c +++ b/drivers/net/wireless/intel/iwlwifi/mvm/tx.c @@ -847,10 +847,7 @@ iwl_mvm_tx_tso_segment(struct sk_buff *skb, unsigned int num_subframes, else if (next) consume_skb(skb); - while (next) { - tmp = next; - next = tmp->next; - + skb_list_walk_safe(next, tmp, next) { memcpy(tmp->cb, cb, sizeof(tmp->cb)); /* * Compute the length of all the data added for the A-MSDU. @@ -880,9 +877,7 @@ iwl_mvm_tx_tso_segment(struct sk_buff *skb, unsigned int num_subframes, skb_shinfo(tmp)->gso_size = 0; } - tmp->prev = NULL; - tmp->next = NULL; - + skb_mark_not_on_list(tmp); __skb_queue_tail(mpdus_skb, tmp); i++; } -- cgit v1.2.3-59-g8ed1b