From 102eb97564c73ea73645b38599c5cbe6f54b030c Mon Sep 17 00:00:00 2001 From: Grant Likely Date: Wed, 23 Jul 2008 21:29:55 -0700 Subject: [PATCH] spi: make spi_board_info.modalias a char array Currently, 'modalias' in the spi_device structure is a 'const char *'. The spi_new_device() function fills in the modalias value from a passed in spi_board_info data block. Since it is a pointer copy, the new spi_device remains dependent on the spi_board_info structure after the new spi_device is registered (no other fields in spi_device directly depend on the spi_board_info structure; all of the other data is copied). This causes a problem when dynamically propulating the list of attached SPI devices. For example, in arch/powerpc, the list of SPI devices can be populated from data in the device tree. With the current code, the device tree adapter must kmalloc() a new spi_board_info structure for each new SPI device it finds in the device tree, and there is no simple mechanism in place for keeping track of these allocations. This patch changes modalias from a 'const char *' to a fixed char array. By copying the modalias string instead of referencing it, the dependency on the spi_board_info structure is eliminated and an outside caller does not need to maintain a separate spi_board_info allocation for each device. If searched through the code to the best of my ability for any references to modalias which may be affected by this change and haven't found anything. It has been tested with the lite5200b platform in arch/powerpc. [dbrownell@users.sourceforge.net: cope with linux-next changes: KOBJ_NAME_LEN obliterated, etc] Signed-off-by: Grant Likely Signed-off-by: David Brownell Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/spi/spi.c | 4 +++- include/linux/spi/spi.h | 2 +- 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 1771b2456bfa..ecca4a6a6f94 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -218,6 +218,8 @@ struct spi_device *spi_new_device(struct spi_master *master, if (!spi_master_get(master)) return NULL; + WARN_ON(strlen(chip->modalias) >= sizeof(proxy->modalias)); + proxy = kzalloc(sizeof *proxy, GFP_KERNEL); if (!proxy) { dev_err(dev, "can't alloc dev for cs%d\n", @@ -229,7 +231,7 @@ struct spi_device *spi_new_device(struct spi_master *master, proxy->max_speed_hz = chip->max_speed_hz; proxy->mode = chip->mode; proxy->irq = chip->irq; - proxy->modalias = chip->modalias; + strlcpy(proxy->modalias, chip->modalias, sizeof(proxy->modalias)); snprintf(proxy->dev.bus_id, sizeof proxy->dev.bus_id, "%s.%u", master->dev.bus_id, diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index b9a76c972084..a9cc29d46653 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -82,7 +82,7 @@ struct spi_device { int irq; void *controller_state; void *controller_data; - const char *modalias; + char modalias[32]; /* * likely need more hooks for more protocol options affecting how