linux-kernel - [PATCH 06/16] ftrace: Replace record newlist with record page list

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Date:	Wed, 21 Dec 2011 07:36:30 -0500
From:	Steven Rostedt <rostedt@...dmis.org>
To:	linux-kernel@...r.kernel.org
Cc:	Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Frederic Weisbecker <fweisbec@...il.com>
Subject: [PATCH 06/16] ftrace: Replace record newlist with record page list

From: Steven Rostedt <srostedt@...hat.com>

As new functions come in to be initalized from mcount to nop,
they are done by groups of pages. Whether it is the core kernel
or a module. There's no need to keep track of these on a per record
basis.

At startup, and as any module is loaded, the functions to be
traced are stored in a group of pages and added to the function
list at the end. We just need to keep a pointer to the first
page of the list that was added, and use that to know where to
start on the list for initializing functions.

Signed-off-by: Steven Rostedt <rostedt@...dmis.org>
---
 include/linux/ftrace.h |    5 +---
 kernel/trace/ftrace.c  |   68 ++++++++++++++++++++++++++----------------------
 2 files changed, 38 insertions(+), 35 deletions(-)

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 3f79bc4..31b9fd7 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -173,10 +173,7 @@ struct dyn_ftrace {
 		unsigned long		ip; /* address of mcount call-site */
 		struct dyn_ftrace	*freelist;
 	};
-	union {
-		unsigned long		flags;
-		struct dyn_ftrace	*newlist;
-	};
+	unsigned long		flags;
 	struct dyn_arch_ftrace		arch;
 };
 
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 2e72188..366d788 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -977,8 +977,6 @@ static struct ftrace_ops global_ops = {
 	.filter_hash		= EMPTY_HASH,
 };
 
-static struct dyn_ftrace *ftrace_new_addrs;
-
 static DEFINE_MUTEX(ftrace_regex_lock);
 
 struct ftrace_page {
@@ -988,6 +986,8 @@ struct ftrace_page {
 	int			size;
 };
 
+static struct ftrace_page *ftrace_new_pgs;
+
 #define ENTRY_SIZE sizeof(struct dyn_ftrace)
 #define ENTRIES_PER_PAGE (PAGE_SIZE / ENTRY_SIZE)
 
@@ -1445,8 +1445,6 @@ ftrace_record_ip(unsigned long ip)
 		return NULL;
 
 	rec->ip = ip;
-	rec->newlist = ftrace_new_addrs;
-	ftrace_new_addrs = rec;
 
 	return rec;
 }
@@ -1936,9 +1934,11 @@ static int ops_traces_mod(struct ftrace_ops *ops)
 
 static int ftrace_update_code(struct module *mod)
 {
+	struct ftrace_page *pg;
 	struct dyn_ftrace *p;
 	cycle_t start, stop;
 	unsigned long ref = 0;
+	int i;
 
 	/*
 	 * When adding a module, we need to check if tracers are
@@ -1960,41 +1960,44 @@ static int ftrace_update_code(struct module *mod)
 	start = ftrace_now(raw_smp_processor_id());
 	ftrace_update_cnt = 0;
 
-	while (ftrace_new_addrs) {
+	for (pg = ftrace_new_pgs; pg; pg = pg->next) {
 
-		/* If something went wrong, bail without enabling anything */
-		if (unlikely(ftrace_disabled))
-			return -1;
+		for (i = 0; i < pg->index; i++) {
+			/* If something went wrong, bail without enabling anything */
+			if (unlikely(ftrace_disabled))
+				return -1;
 
-		p = ftrace_new_addrs;
-		ftrace_new_addrs = p->newlist;
-		p->flags = ref;
+			p = &pg->records[i];
+			p->flags = ref;
 
-		/*
-		 * Do the initial record conversion from mcount jump
-		 * to the NOP instructions.
-		 */
-		if (!ftrace_code_disable(mod, p))
-			break;
+			/*
+			 * Do the initial record conversion from mcount jump
+			 * to the NOP instructions.
+			 */
+			if (!ftrace_code_disable(mod, p))
+				break;
 
-		ftrace_update_cnt++;
+			ftrace_update_cnt++;
 
-		/*
-		 * If the tracing is enabled, go ahead and enable the record.
-		 *
-		 * The reason not to enable the record immediatelly is the
-		 * inherent check of ftrace_make_nop/ftrace_make_call for
-		 * correct previous instructions.  Making first the NOP
-		 * conversion puts the module to the correct state, thus
-		 * passing the ftrace_make_call check.
-		 */
-		if (ftrace_start_up && ref) {
-			int failed = __ftrace_replace_code(p, 1);
-			if (failed)
-				ftrace_bug(failed, p->ip);
+			/*
+			 * If the tracing is enabled, go ahead and enable the record.
+			 *
+			 * The reason not to enable the record immediatelly is the
+			 * inherent check of ftrace_make_nop/ftrace_make_call for
+			 * correct previous instructions.  Making first the NOP
+			 * conversion puts the module to the correct state, thus
+			 * passing the ftrace_make_call check.
+			 */
+			if (ftrace_start_up && ref) {
+				int failed = __ftrace_replace_code(p, 1);
+				if (failed)
+					ftrace_bug(failed, p->ip);
+			}
 		}
 	}
 
+	ftrace_new_pgs = NULL;
+
 	stop = ftrace_now(raw_smp_processor_id());
 	ftrace_update_time = stop - start;
 	ftrace_update_tot_cnt += ftrace_update_cnt;
@@ -3632,6 +3635,9 @@ static int ftrace_process_locs(struct module *mod,
 			break;
 	}
 
+	/* These new locations need to be initialized */
+	ftrace_new_pgs = pg;
+
 	/*
 	 * We only need to disable interrupts on start up
 	 * because we are modifying code that an interrupt
-- 
1.7.7.3



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