From dc61d28247b284b857d1ee93d7083b09cc057b82 Mon Sep 17 00:00:00 2001
From: Adam Rutkowski <adam.j.rutkowski@intel.com>
Date: Fri, 18 Oct 2019 17:19:08 -0400
Subject: [PATCH] Replace runtime allocation in logger with static percpu
 buffer

Signed-off-by: Adam Rutkowski <adam.j.rutkowski@intel.com>
---
 modules/cas_cache/context.c | 46 ++++++++++++++++++++++++++++++++-----
 1 file changed, 40 insertions(+), 6 deletions(-)

diff --git a/modules/cas_cache/context.c b/modules/cas_cache/context.c
index d653abf..8579286 100644
--- a/modules/cas_cache/context.c
+++ b/modules/cas_cache/context.c
@@ -297,6 +297,28 @@ static void _cas_ctx_metadata_updater_stop(ocf_metadata_updater_t mu)
 	return cas_stop_metadata_updater_thread(mu);
 }
 
+#define CAS_LOG_FORMAT_STRING_MAX_LEN 256
+
+static int _cas_ctx_logger_open(ocf_logger_t logger)
+{
+	void __percpu *priv;
+
+	priv = alloc_percpu(char[CAS_LOG_FORMAT_STRING_MAX_LEN]);
+	if (!priv)
+		return -ENOMEM;
+
+	ocf_logger_set_priv(logger, priv);
+
+	return 0;
+}
+
+static void _cas_ctx_logger_close(ocf_logger_t logger)
+{
+	void __percpu *priv = ocf_logger_get_priv(logger);
+
+	free_percpu(priv);
+}
+
 /*
  *
  */
@@ -313,17 +335,27 @@ static int _cas_ctx_logger_print(ocf_logger_t logger, ocf_logger_lvl_t lvl,
 		[log_info] = KERN_INFO,
 		[log_debug] = KERN_DEBUG,
 	};
-	char *format;
+	int ret;
+	void __percpu *priv;
+	char *buf;
+
 	if (((unsigned)lvl) >= sizeof(level)/sizeof(level[0]))
 		return -EINVAL;
 
-	format = kasprintf(GFP_ATOMIC, "%s%s", level[lvl], fmt);
-	if (!format)
-		return -ENOMEM;
+	priv = ocf_logger_get_priv(logger);
+	buf = get_cpu_ptr(priv);
 
-	vprintk(format, args);
+	/* Try to prepend log level prefix to format string. If this fails
+	 * for any reason, we just fall back to user provided format string */
+	ret = snprintf(buf, CAS_LOG_FORMAT_STRING_MAX_LEN, "%s%s", level[lvl],
+			fmt);
+	if (ret >= CAS_LOG_FORMAT_STRING_MAX_LEN)
+		vprintk(fmt, args);
+	else
+		vprintk(buf, args);
 
-	kfree(format);
+
+	put_cpu_ptr(priv);
 
 	return 0;
 }
@@ -381,6 +413,8 @@ static const struct ocf_ctx_config ctx_cfg = {
 		},
 
 		.logger = {
+			.open = _cas_ctx_logger_open,
+			.close = _cas_ctx_logger_close,
 			.print = _cas_ctx_logger_print,
 			.print_rl = _cas_ctx_logger_print_rl,
 			.dump_stack = _cas_ctx_logger_dump_stack,