linux-kernel - [PATCH] proc/wchan: Use printk format instead of lookup_symbol

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Date:   Thu, 17 Dec 2020 17:54:13 +0100
From:   Helge Deller <deller@....de>
To:     Alexey Dobriyan <adobriyan@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: [PATCH] proc/wchan: Use printk format instead of lookup_symbol_name()

To resolve the symbol fuction name for wchan, use the printk format
specifier %ps instead of manually looking up the symbol function name
via lookup_symbol_name().

Signed-off-by: Helge Deller <deller@....de>

diff --git a/fs/proc/base.c b/fs/proc/base.c
index b362523a9829..c4593e1cafa4 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -67,7 +67,6 @@
 #include <linux/mm.h>
 #include <linux/swap.h>
 #include <linux/rcupdate.h>
-#include <linux/kallsyms.h>
 #include <linux/stacktrace.h>
 #include <linux/resource.h>
 #include <linux/module.h>
@@ -386,19 +385,17 @@ static int proc_pid_wchan(struct seq_file *m, struct pid_namespace *ns,
 			  struct pid *pid, struct task_struct *task)
 {
 	unsigned long wchan;
-	char symname[KSYM_NAME_LEN];

-	if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS))
-		goto print0;
+	if (ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS))
+		wchan = get_wchan(task);
+	else
+		wchan = 0;

-	wchan = get_wchan(task);
-	if (wchan && !lookup_symbol_name(wchan, symname)) {
-		seq_puts(m, symname);
-		return 0;
-	}
+	if (wchan)
+		seq_printf(m, "%ps", (void *) wchan);
+	else
+		seq_putc(m, '0');

-print0:
-	seq_putc(m, '0');
 	return 0;
 }
 #endif /* CONFIG_KALLSYMS */