From 43cfe68b5a7181f1e8a51c28c12cc0b7658ebbed Mon Sep 17 00:00:00 2001
From: Himateja Reddy <hmreddy@codeaurora.org>
Date: Mon, 22 Jun 2020 14:32:24 -0700
Subject: [PATCH] msm: adsprpc: limit number of cached buffers

Current code allocates new buffer during invoke, if no free buffer
found in cached buffer list. During invoke return new buffer is
added to the cached buffer list. In Async RPC as many invocations
come in short duration, there is a chance of buffers piling up in
cached buffer list. Limit the number of buffers cached under
cached buffer list to MAX_CACHED_BUFS.

Change-Id: If62406f35397843986ae033ab2cb027ed2356fd1
Signed-off-by: Himateja Reddy <hmreddy@codeaurora.org>
---
 drivers/char/adsprpc.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/char/adsprpc.c b/drivers/char/adsprpc.c
index 1d1f44e44fdb..ac9a409ba3b7 100644
--- a/drivers/char/adsprpc.c
+++ b/drivers/char/adsprpc.c
@@ -182,6 +182,9 @@
 #define INIT_MEMLEN_MAX  (8*1024*1024)
 #define MAX_CACHE_BUF_SIZE (8*1024*1024)
 
+/* Maximum buffers cached in cached buffer list */
+#define MAX_CACHED_BUFS   (32)
+
 /* Max no. of persistent headers pre-allocated per process */
 #define MAX_PERSISTENT_HEADERS    (25)
 
@@ -503,6 +506,7 @@ struct fastrpc_file {
 	spinlock_t hlock;
 	struct hlist_head maps;
 	struct hlist_head cached_bufs;
+	uint32_t num_cached_buf;
 	struct hlist_head remote_bufs;
 	struct fastrpc_ctx_lst clst;
 	struct fastrpc_session_ctx *sctx;
@@ -741,11 +745,17 @@ static void fastrpc_buf_free(struct fastrpc_buf *buf, int cache)
 	}
 	if (cache && buf->size < MAX_CACHE_BUF_SIZE) {
 		spin_lock(&fl->hlock);
+		if (fl->num_cached_buf > MAX_CACHED_BUFS) {
+			spin_unlock(&fl->hlock);
+			goto skip_buf_cache;
+		}
 		hlist_add_head(&buf->hn, &fl->cached_bufs);
+		fl->num_cached_buf++;
 		spin_unlock(&fl->hlock);
 		buf->type = -1;
 		return;
 	}
+skip_buf_cache:
 	if (buf->type == USERHEAP_BUF) {
 		spin_lock(&fl->hlock);
 		hlist_del_init(&buf->hn_rem);
@@ -790,6 +800,7 @@ static void fastrpc_cached_buf_list_free(struct fastrpc_file *fl)
 		spin_lock(&fl->hlock);
 		hlist_for_each_entry_safe(buf, n, &fl->cached_bufs, hn) {
 			hlist_del_init(&buf->hn);
+			fl->num_cached_buf--;
 			free = buf;
 			break;
 		}
@@ -1312,8 +1323,10 @@ static inline bool fastrpc_get_cached_buf(struct fastrpc_file *fl,
 		if (buf->size >= size && (!fr || fr->size > buf->size))
 			fr = buf;
 	}
-	if (fr)
+	if (fr) {
 		hlist_del_init(&fr->hn);
+		fl->num_cached_buf--;
+	}
 	spin_unlock(&fl->hlock);
 	if (fr) {
 		fr->type = buf_type;
@@ -5044,6 +5057,7 @@ static int fastrpc_device_open(struct inode *inode, struct file *filp)
 	INIT_HLIST_HEAD(&fl->maps);
 	INIT_HLIST_HEAD(&fl->perf);
 	INIT_HLIST_HEAD(&fl->cached_bufs);
+	fl->num_cached_buf = 0;
 	INIT_HLIST_HEAD(&fl->remote_bufs);
 	init_waitqueue_head(&fl->async_wait_queue);
 	INIT_HLIST_NODE(&fl->hn);