core: Update to the new chaining format from physical driver

Use the skb_walk_frags() format to unchain packets instead of
recursively using frag_list. Otherwise this could result in the
following -

apps_ipa_packet_receive_notify: 332 callbacks suppressed
ipa-wan apps_ipa_packet_receive_notify:1660 fail on netif_receive_skb
ipa-wan apps_ipa_packet_receive_notify:1660 fail on netif_receive_skb
ipa-wan apps_ipa_packet_receive_notify:1660 fail on netif_receive_skb
Insufficient stack space to handle exception!
Kernel panic - not syncing: kernel stack overflow
Call trace:
dump_backtrace.cfi_jt+0x0/0x8
dump_stack_lvl+0x98/0xe8
panic+0x190/0x458
panic_bad_stack+0x1c8/0x200
patch_alternative+0x0/0x124
__bad_stack+0x90/0x94
arch_stack_walk+0x34/0x144
save_stack+0x8c/0xf4
free_pcp_prepare+0x378/0x430
free_unref_page+0x40/0x1d4
free_compound_page+0x8c/0xd8
skb_release_data+0x238/0x460
kfree_skb+0x8c/0x214
skb_release_data+0x28c/0x460
kfree_skb+0x8c/0x214
skb_release_data+0x28c/0x460
kfree_skb+0x8c/0x214
...
skb_release_data+0x28c/0x460
kfree_skb+0x8c/0x214
skb_release_data+0x28c/0x460
kfree_skb+0x8c/0x214
enqueue_to_backlog+0x104/0x3ac
netif_receive_skb_internal+0x114/0x154
netif_receive_skb+0x20/0x1a4
apps_ipa_packet_receive_notify+0xbc/0x43c [ipam]
ipa3_wan_rx_pyld_hdlr+0xa0/0xbf0 [ipam]
ipa3_rx_napi_chain+0x310/0x594 [ipam]
ipa3_rx_poll+0x1bc/0x8e0 [ipam]
ipa3_rmnet_poll+0x28/0xa8 [ipam]
__napi_poll+0x64/0x268
net_rx_action+0x144/0x3f8
_stext+0x1dc/0x6dc
run_ksoftirqd+0x50/0xac
smpboot_thread_fn+0x1b0/0x400
kthread+0x17c/0x1e0
ret_from_fork+0x10/0x20

CRs-Fixed: 3372964
Change-Id: I9f252e018c10e11ba88ed8626b776bd65286be96
Signed-off-by: Subash Abhinov Kasiviswanathan <[email protected]>

core/rmnet_descriptor.c

@@ -1,5 +1,5 @@
 /* Copyright (c) 2013-2021, The Linux Foundation. All rights reserved.
- * Copyright (c) 2022, Qualcomm Innovation Center, Inc. All rights reserved.
+ * Copyright (c) 2022-2023, Qualcomm Innovation Center, Inc. All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 and
@@ -1913,6 +1913,7 @@ void rmnet_frag_ingress_handler(struct sk_buff *skb,
 	LIST_HEAD(desc_list);
 	bool skip_perf = (skb->priority == 0xda1a);
 	u64 chain_count = 0;
+	struct sk_buff *head = skb;
 
 	/* Deaggregation and freeing of HW originating
 	 * buffers is done within here
@@ -1935,8 +1936,14 @@ void rmnet_frag_ingress_handler(struct sk_buff *skb,
 			}
 		}
 
-		skb_frag = skb_shinfo(skb)->frag_list;
-		skb_shinfo(skb)->frag_list = NULL;
+		if (skb == head) {
+			skb_frag = skb_shinfo(skb)->frag_list;
+			skb_shinfo(skb)->frag_list = NULL;
+		} else {
+			skb_frag = skb->next;
+			skb->next = NULL;
+		}
+
 		consume_skb(skb);
 		skb = skb_frag;
 	}