[MTD NAND] Modify check for modules registering NAND devices without ->owner

Linux-MTD Mailing List linux-mtd at lists.infradead.org
Sun May 14 11:59:01 EDT 2006

Commit:     52239da1b06ff445bf71d35e04d8ce74e4c6fe7b
Parent:     0d4e30d26a279f1b6a008a233a6835ad2af571e4
Author:     David Woodhouse <dwmw2 at infradead.org>
AuthorDate: Sun May 14 16:54:39 2006 +0100
Commit:     David Woodhouse <dwmw2 at infradead.org>
CommitDate: Sun May 14 16:54:39 2006 +0100

    [MTD NAND] Modify check for modules registering NAND devices without ->owner
    Make it work even with compilers which lack the wit to notice that
    THIS_MODULE is always non-NULL. Use #ifdef MODULE instead. It's only
    a temporary debugging check anyway.
    Signed-off-by: David Woodhouse <dwmw2 at infradead.org>

 drivers/mtd/nand/nand_base.c |   17 +++++++++++------
 1 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 42cff0a..08dffb7 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -2312,6 +2312,15 @@ static void nand_resume(struct mtd_info 
+/* module_text_address() isn't exported, and it's mostly a pointless
+   test if this is a module _anyway_ -- they'd have to try _really_ hard
+   to call us from in-kernel code if the core NAND support is modular. */
+#ifdef MODULE
+#define caller_is_module() (1)
+#define caller_is_module() module_text_address((unsigned long)__builtin_return_address(0))
  * nand_scan - [NAND Interface] Scan for the NAND device
  * @mtd:	MTD device structure
@@ -2330,12 +2339,8 @@ int nand_scan(struct mtd_info *mtd, int 
 	int i, nand_maf_id, nand_dev_id, busw, maf_id;
 	struct nand_chip *this = mtd->priv;
-	/* module_text_address() isn't exported. But if _this_ is a module,
-	   it's a fairly safe bet that its caller is a module too... and
-	   that means the call to module_text_address() gets optimised out
-	   without having to resort to ifdefs */
-	if (!mtd->owner && (THIS_MODULE ||
-	    module_text_address((unsigned long)__builtin_return_address(0)))) {
+	/* Many callers got this wrong, so check for it for a while... */
+	if (!mtd->owner && caller_is_module()) {
 		printk(KERN_CRIT "nand_scan() called with NULL mtd->owner!\n");

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