spi: Fix double IDR allocation with DT aliases

commit 04b2d03a75652bda989de1595048f0501dc0c0a0 upstream.

If the SPI bus number is provided by a DT alias, idr_alloc() is called
twice, leading to:

    WARNING: CPU: 1 PID: 1 at drivers/spi/spi.c:2179 spi_register_controller+0x11c/0x5d8
    couldn't get idr

Fix this by moving the handling of fixed SPI bus numbers up, before the
DT handling code fills in ctlr->bus_num.

Fixes: 1a4327fbf4554d5b ("spi: fix IDR collision on systems with both fixed and dynamic SPI bus numbers")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Cc: Kirill Kapranov <kirill.kapranov@compulab.co.il>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 780a32175ec09ed15250edc4c8e96d02aa24a4b0..670dbb7a8500a228e4c7d13e1aad192b5a2e8d7d 100644 (file)
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -2108,8 +2108,17 @@ int spi_register_controller(struct spi_controller *ctlr)
         */
        if (ctlr->num_chipselect == 0)
                return -EINVAL;
-       /* allocate dynamic bus number using Linux idr */
-       if ((ctlr->bus_num < 0) && ctlr->dev.of_node) {
+       if (ctlr->bus_num >= 0) {
+               /* devices with a fixed bus num must check-in with the num */
+               mutex_lock(&board_lock);
+               id = idr_alloc(&spi_master_idr, ctlr, ctlr->bus_num,
+                       ctlr->bus_num + 1, GFP_KERNEL);
+               mutex_unlock(&board_lock);
+               if (WARN(id < 0, "couldn't get idr"))
+                       return id == -ENOSPC ? -EBUSY : id;
+               ctlr->bus_num = id;
+       } else if (ctlr->dev.of_node) {
+               /* allocate dynamic bus number using Linux idr */
                id = of_alias_get_id(ctlr->dev.of_node, "spi");
                if (id >= 0) {
                        ctlr->bus_num = id;
@@ -2135,15 +2144,6 @@ int spi_register_controller(struct spi_controller *ctlr)
                if (WARN(id < 0, "couldn't get idr"))
                        return id;
                ctlr->bus_num = id;
-       } else {
-               /* devices with a fixed bus num must check-in with the num */
-               mutex_lock(&board_lock);
-               id = idr_alloc(&spi_master_idr, ctlr, ctlr->bus_num,
-                       ctlr->bus_num + 1, GFP_KERNEL);
-               mutex_unlock(&board_lock);
-               if (WARN(id < 0, "couldn't get idr"))
-                       return id == -ENOSPC ? -EBUSY : id;
-               ctlr->bus_num = id;
        }
        INIT_LIST_HEAD(&ctlr->queue);
        spin_lock_init(&ctlr->queue_lock);