spi: Fix double IDR allocation with DT aliases

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>

1 files changed, 11 insertions, 11 deletions

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index a00d006d4c3a..9da0bc5a036c 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -2143,8 +2143,17 @@ 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;
@@ -2170,15 +2179,6 @@ 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);