qualcommax: skbuff_recycle: add proc option to enable/disable

There are instances where `skbuff_recycle` messes up skb headers causing
various issues in network related activities. This was initially meant
to resolve issues with memory usage issues on 6.1.

Introduce a proc option to enable or disable skbuff_recycle. The default
is to have it enabled. Users on 512M platforms should test if memory
leaks still occur with this option disabled.

echo 0 > /proc/net/skb_recycler/skb_recycler_enable

echo 1 > /proc/net/skb_recycler/skb_recycler_enable

NOTE: There is a new script in `qca-nss-drv` that will automatically
manage this as an UCI configurable option.

commit 217a4fa43ba2ad0a02e8080dfde11ad23534aa8c (HEAD -> NSS-12.5-K6.x)
Author:     Sean Khan <datapronix@protonmail.com>
AuthorDate: Sat Jul 13 18:43:52 2024 -0400
Commit:     Sean Khan <datapronix@protonmail.com>
CommitDate: Sat Jul 13 18:43:52 2024 -0400

    nss-drv: add skb_recycler init script

Signed-off-by: Sean Khan <datapronix@protonmail.com>

target/linux/qualcommax/files/net/core/skbuff_recycle.c

@@ -33,14 +33,20 @@ static struct global_recycler glob_recycler;
 static int skb_recycle_spare_max_skbs = SKB_RECYCLE_SPARE_MAX_SKBS;
 #endif
 
+static int skb_recycling_enable = 1;
 inline struct sk_buff *skb_recycler_alloc(struct net_device *dev,
-					  unsigned int length)
+					  unsigned int length, bool reset_skb)
 {
 	unsigned long flags;
 	struct sk_buff_head *h;
 	struct sk_buff *skb = NULL;
 	struct sk_buff *ln = NULL;
 
+	/* Allocate the recycled skbs if the skb_recycling_enable */
+	if (unlikely(!skb_recycling_enable)) {
+		return NULL;
+	}
+
 	if (unlikely(length > SKB_RECYCLE_SIZE))
 		return NULL;
 
@@ -106,10 +112,15 @@ inline struct sk_buff *skb_recycler_alloc(struct net_device *dev,
 		 * zero most of the structure so prefetch the start
 		 * of the shinfo region now so it's in the D-cache
 		 * before we start to write that.
+		 * For buffers recycled by PPE DS rings, the packets wouldnt
+		 * have been processed by host and hence shinfo reset can be
+		 * avoided. Avoid it if specifically requested for it
+		 * (by DS rings), and the buffer is found to be recycled by
+		 * DS previously
 		 */
+
 		shinfo = skb_shinfo(skb);
 		prefetchw(shinfo);
-
 		zero_struct(skb, offsetof(struct sk_buff, tail));
 		refcount_set(&skb->users, 1);
 		skb->mac_header = (typeof(skb->mac_header))~0U;
@@ -131,6 +142,12 @@ inline bool skb_recycler_consume(struct sk_buff *skb)
 	unsigned long flags;
 	struct sk_buff_head *h;
 	struct sk_buff *ln = NULL;
+
+	/* Consume the skbs if the skb_recycling_enable */
+	if (unlikely(!skb_recycling_enable)) {
+		return false;
+	}
+
 	/* Can we recycle this skb?  If not, simply return that we cannot */
 	if (unlikely(!consume_skb_can_recycle(skb, SKB_RECYCLE_MIN_SIZE,
 					      SKB_RECYCLE_MAX_SIZE)))
@@ -237,7 +254,9 @@ inline bool skb_recycler_consume(struct sk_buff *skb)
 inline bool skb_recycler_consume_list_fast(struct sk_buff_head *skb_list)
 {
 	struct sk_buff *skb = NULL, *next = NULL;
-
+	if (unlikely(!skb_recycling_enable)) {
+		return false;
+	}
 	skb_queue_walk_safe(skb_list, skb, next) {
 		if (skb) {
 			__skb_unlink(skb, skb_list);
@@ -253,6 +272,11 @@ inline bool skb_recycler_consume_list_fast(struct sk_buff_head *skb_list)
 	unsigned long flags;
 	struct sk_buff_head *h;
 
+	/* Allocate the recycled skbs if the skb_recycling_enable */
+	if (unlikely(!skb_recycling_enable)) {
+		return false;
+	}
+
 	h = &get_cpu_var(recycle_list);
 	local_irq_save(flags);
 	/* Attempt to enqueue the CPU hot recycle list first */
@@ -537,6 +561,46 @@ static const struct proc_ops proc_skb_max_spare_skbs_fops = {
 };
 #endif /* CONFIG_SKB_RECYCLER_MULTI_CPU */
 
+/* procfs: skb_recycler_enable
+ * By default, recycler is disabled for QSDK_512 profile.
+ * Can be enabled for alder/miami QSDK_512 profile.
+ */
+static int proc_skb_recycler_enable_show(struct seq_file *seq, void *v) {
+	seq_printf(seq, "%d\n", skb_recycling_enable);
+	return 0;
+}
+
+static int proc_skb_recycle_enable_open(struct inode *inode, struct file *file) {
+	return single_open(file, proc_skb_recycler_enable_show,
+			   pde_data(inode));
+}
+
+static ssize_t proc_skb_recycle_enable_write(struct file *file,
+					     const char __user *buf,
+					     size_t count, loff_t *ppos) {
+	int ret;
+	int enable;
+	char buffer[13];
+
+	memset(buffer, 0, sizeof(buffer));
+	if (count > sizeof(buffer) - 1)
+		count = sizeof(buffer) - 1;
+	if (copy_from_user(buffer, buf, count) != 0)
+		return -EFAULT;
+	ret = kstrtoint(strstrip(buffer), 10, &enable);
+	if (ret == 0 && enable >= 0)
+		skb_recycling_enable = enable;
+
+	return count;
+}
+
+static const struct proc_ops proc_skb_recycle_enable_fops = {
+	.proc_open = proc_skb_recycle_enable_open,
+	.proc_read = seq_read,
+	.proc_write = proc_skb_recycle_enable_write,
+	.proc_release = single_release,
+};
+
 static void skb_recycler_init_procfs(void)
 {
 	proc_net_skbrecycler = proc_mkdir("skb_recycler", init_net.proc_net);
@@ -570,6 +634,13 @@ static void skb_recycler_init_procfs(void)
 			 &proc_skb_max_spare_skbs_fops))
 		pr_err("cannot create proc net skb_recycle max_spare_skbs\n");
 #endif
+
+	if (!proc_create("skb_recycler_enable",
+			 S_IRUGO | S_IWUGO,
+			 proc_net_skbrecycler,
+			 &proc_skb_recycle_enable_fops))
+		pr_err("cannot create proc net skb_recycle enable\n");
+
 }
 
 void __init skb_recycler_init(void)
@@ -607,6 +678,7 @@ void __init skb_recycler_init(void)
 
 void skb_recycler_print_all_lists(void)
 {
+
 	unsigned long flags;
 	int cpu;
 #ifdef CONFIG_SKB_RECYCLER_MULTI_CPU
@@ -637,6 +709,7 @@ void skb_recycler_print_all_lists(void)
 
 	local_irq_restore(flags);
 	preempt_enable();
+
 }
 
 #ifdef CONFIG_SKB_FAST_RECYCLABLE_DEBUG_ENABLE
@@ -717,11 +790,11 @@ static inline bool consume_skb_can_fast_recycle_debug(const struct sk_buff *skb,
 }
 
 /**
- *      check_skb_fast_recyclable - Debug API to flag any sanity check failures
+ * check_skb_fast_recyclable - Debug API to flag any sanity check failures
- *      			    on a fast recycled skb
+ * 			    on a fast recycled skb
- *      @skb: buffer to be checked
+ * @skb: buffer to be checked
  *
- *      Checks skb recyclability
+ * Checks skb recyclability
  */
 void check_skb_fast_recyclable(struct sk_buff *skb)
 {

target/linux/qualcommax/files/net/core/skbuff_recycle.h

@@ -162,20 +162,25 @@ static inline bool consume_skb_can_recycle(const struct sk_buff *skb,
 	if (unlikely(skb_pfmemalloc(skb)))
 		return false;
 
+	if (skb->active_extensions)
+		return false;
+
 	return true;
 }
 
 #ifdef CONFIG_SKB_RECYCLER
 void __init skb_recycler_init(void);
-struct sk_buff *skb_recycler_alloc(struct net_device *dev, unsigned int length);
+struct sk_buff *skb_recycler_alloc(struct net_device *dev, unsigned int length, bool reset_skb);
 bool skb_recycler_consume(struct sk_buff *skb);
 bool skb_recycler_consume_list_fast(struct sk_buff_head *skb_list);
 void skb_recycler_print_all_lists(void);
+void skb_recycler_clear_flags(struct sk_buff *skb);
 #else
 #define skb_recycler_init()  {}
-#define skb_recycler_alloc(dev, len) NULL
+#define skb_recycler_alloc(dev, len, reset_skb) NULL
 #define skb_recycler_consume(skb) false
 #define skb_recycler_consume_list_fast(skb_list) false
 #define skb_recycler_print_all_lists() false
+#define skb_recycler_clear_flags(skb) {}
 #endif
 #endif