initramfs: cleanup initrd freeing

Factor the kexec logic into a separate helper, and then inline the rest of
free_initrd into the only caller.

Link: http://lkml.kernel.org/r/20190213174621.29297-4-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>	[arm64]
Cc: Geert Uytterhoeven <geert@linux-m68k.org>	[m68k]
Cc: Steven Price <steven.price@arm.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Guan Xuetao <gxt@pku.edu.cn>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

init/initramfs.c

@@ -518,37 +518,35 @@ extern unsigned long __initramfs_size;
 #include <linux/initrd.h>
 #include <linux/kexec.h>
 
-static void __init free_initrd(void)
-{
 #ifdef CONFIG_KEXEC_CORE
+static bool kexec_free_initrd(void)
+{
 	unsigned long crashk_start = (unsigned long)__va(crashk_res.start);
 	unsigned long crashk_end   = (unsigned long)__va(crashk_res.end);
-#endif
-	if (do_retain_initrd)
-		goto skip;
 
-#ifdef CONFIG_KEXEC_CORE
 	/*
 	 * If the initrd region is overlapped with crashkernel reserved region,
 	 * free only memory that is not part of crashkernel region.
 	 */
-	if (initrd_start < crashk_end && initrd_end > crashk_start) {
-		/*
-		 * Initialize initrd memory region since the kexec boot does
-		 * not do.
-		 */
-		memset((void *)initrd_start, 0, initrd_end - initrd_start);
-		if (initrd_start < crashk_start)
-			free_initrd_mem(initrd_start, crashk_start);
-		if (initrd_end > crashk_end)
-			free_initrd_mem(crashk_end, initrd_end);
-	} else
-#endif
-		free_initrd_mem(initrd_start, initrd_end);
-skip:
-	initrd_start = 0;
-	initrd_end = 0;
+	if (initrd_start >= crashk_end || initrd_end <= crashk_start)
+		return false;
+
+	/*
+	 * Initialize initrd memory region since the kexec boot does not do.
+	 */
+	memset((void *)initrd_start, 0, initrd_end - initrd_start);
+	if (initrd_start < crashk_start)
+		free_initrd_mem(initrd_start, crashk_start);
+	if (initrd_end > crashk_end)
+		free_initrd_mem(crashk_end, initrd_end);
+	return true;
 }
+#else
+static inline bool kexec_free_initrd(void)
+{
+	return false;
+}
+#endif /* CONFIG_KEXEC_CORE */
 
 #ifdef CONFIG_BLK_DEV_RAM
 #define BUF_SIZE 1024
@@ -642,7 +640,16 @@ static int __init populate_rootfs(void)
 			printk(KERN_EMERG "Initramfs unpacking failed: %s\n", err);
 #endif
 	}
-	free_initrd();
+
+	/*
+	 * If the initrd region is overlapped with crashkernel reserved region,
+	 * free only memory that is not part of crashkernel region.
+	 */
+	if (!do_retain_initrd && !kexec_free_initrd())
+		free_initrd_mem(initrd_start, initrd_end);
+	initrd_start = 0;
+	initrd_end = 0;
+
 	flush_delayed_fput();
 	return 0;
 }