spi: fix IDR collision on systems with both fixed and dynamic SPI bus numbers

commit 1a4327fbf4554d5b78d75b19a13d40d6de220159 upstream.

On systems where some controllers get a dynamic ID assigned and some have
a fixed number (e.g. from ACPI tables), the current implementation might
run into an IDR collision: in case of a fixed bus number is gotten by a
driver (but not marked busy in IDR tree) and a driver with dynamic bus
number gets the same ID and predictably fails.

Fix this by means of checking-in fixed IDsin IDR as far as dynamic ones
at the moment of the controller registration.

Fixes: 9b61e302210e (spi: Pick spi bus number from Linux idr or spi alias)
Signed-off-by: Kirill Kapranov <kirill.kapranov@compulab.co.il>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index f85d30dc91878dbb8472b3bc8fec69ff2244fb6a..780a32175ec09ed15250edc4c8e96d02aa24a4b0 100644 (file)
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -2135,6 +2135,15 @@ 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);