mtd: fsl-quadspi: Fix module unbound

[Linux-MTD Mailing List]

Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=cfe4af3aac3bd63e9caf548157805ca46ad7b073
Commit:     cfe4af3aac3bd63e9caf548157805ca46ad7b073
Parent:     fcc87a95195236b0935183361a72e4a98bf577d8
Author:     Fabio Estevam <fabio.estevam at freescale.com>
AuthorDate: Tue Jan 13 20:14:15 2015 -0200
Committer:  Brian Norris <computersforpeace at gmail.com>
CommitDate: Tue Jan 20 12:37:57 2015 -0800

    mtd: fsl-quadspi: Fix module unbound
    
    When removing the fsl-quadspi module and running 'cat /proc/mtd' afterwards,
    we see garbage data like:
    
    $ rmmod  fsl-quadspi
    $ cat /proc/mtd
    dev:    size   erasesize  name
    mtd0: 00000000 00000000 "(null)"
    mtd0: 00000000 00000000 "(null)"
    mtd0: 00000000 00000000 "(null)"
    ...
    mtd0: a22296c6c756e28 00000000 "(null)"
    mtd0: a22296c6c756e28 3064746d "(null)"
    
    If we continue doing multiple module load/unload operations, then it will also
    lead to a kernel crash.
    
    The reason for this is due to the wrong mtd index used in
    mtd_device_unregister() in the remove function.
    
    We need to keep the mtd unregister index aligned with the one used in the probe
    function, which means we need to take into account the 'has_second_chip'
    property. By doing so we can guarantee that the mtd index is the same in the
    registration and unregistration functions.
    
    With this patch applied we can load/unload the fsl-quadspi driver several times
    and it will result in no crash.
    
    Signed-off-by: Fabio Estevam <fabio.estevam at freescale.com>
    Acked-by: Huang Shijie <shijie.huang at intel.com>
    Tested-by: Frank Li <Frank.Li at freescale.com>
    Acked-by: Allen Xu <han.xu at freescale.com>
    Signed-off-by: Brian Norris <computersforpeace at gmail.com>
---
 drivers/mtd/spi-nor/fsl-quadspi.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/drivers/mtd/spi-nor/fsl-quadspi.c b/drivers/mtd/spi-nor/fsl-quadspi.c
index 9d608007..a46bea3 100644
--- a/drivers/mtd/spi-nor/fsl-quadspi.c
+++ b/drivers/mtd/spi-nor/fsl-quadspi.c
@@ -227,6 +227,7 @@ struct fsl_qspi {
 	u32 nor_num;
 	u32 clk_rate;
 	unsigned int chip_base_addr; /* We may support two chips. */
+	bool has_second_chip;
 };
 
 static inline int is_vybrid_qspi(struct fsl_qspi *q)
@@ -783,7 +784,6 @@ static int fsl_qspi_probe(struct platform_device *pdev)
 	struct spi_nor *nor;
 	struct mtd_info *mtd;
 	int ret, i = 0;
-	bool has_second_chip = false;
 	const struct of_device_id *of_id =
 			of_match_device(fsl_qspi_dt_ids, &pdev->dev);
 
@@ -860,14 +860,14 @@ static int fsl_qspi_probe(struct platform_device *pdev)
 		goto irq_failed;
 
 	if (of_get_property(np, "fsl,qspi-has-second-chip", NULL))
-		has_second_chip = true;
+		q->has_second_chip = true;
 
 	/* iterate the subnodes. */
 	for_each_available_child_of_node(dev->of_node, np) {
 		char modalias[40];
 
 		/* skip the holes */
-		if (!has_second_chip)
+		if (!q->has_second_chip)
 			i *= 2;
 
 		nor = &q->nor[i];
@@ -943,9 +943,12 @@ static int fsl_qspi_probe(struct platform_device *pdev)
 	return 0;
 
 last_init_failed:
-	for (i = 0; i < q->nor_num; i++)
+	for (i = 0; i < q->nor_num; i++) {
+		/* skip the holes */
+		if (!q->has_second_chip)
+			i *= 2;
 		mtd_device_unregister(&q->mtd[i]);
-
+	}
 irq_failed:
 	clk_disable_unprepare(q->clk);
 clk_failed:
@@ -960,8 +963,12 @@ static int fsl_qspi_remove(struct platform_device *pdev)
 	struct fsl_qspi *q = platform_get_drvdata(pdev);
 	int i;
 
-	for (i = 0; i < q->nor_num; i++)
+	for (i = 0; i < q->nor_num; i++) {
+		/* skip the holes */
+		if (!q->has_second_chip)
+			i *= 2;
 		mtd_device_unregister(&q->mtd[i]);
+	}
 
 	/* disable the hardware */
 	writel(QUADSPI_MCR_MDIS_MASK, q->iobase + QUADSPI_MCR);