Messages in this thread Patch in this message | | | From | Arnd Bergmann <> | Subject | [PATCH 2/2] staging/vc04_services: add CONFIG_OF dependency | Date | Wed, 1 Mar 2017 23:50:19 +0100 |
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After several hours of debugging this obviously bogus but elaborate gcc-7.0.1 warning,
drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c: In function 'vchiq_complete_bulk': drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c:603:4: error: argument 2 null where non-null expected [-Werror=nonnull] memcpy((char *)page_address(pages[0]) + ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ pagelist->offset, ~~~~~~~~~~~~~~~~~ fragments, ~~~~~~~~~~ head_bytes); ~~~~~~~~~~~ In file included from include/linux/string.h:18:0, from include/linux/bitmap.h:8, from include/linux/cpumask.h:11, from include/linux/interrupt.h:9, from drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c:37: arch/arm/include/asm/string.h:16:15: note: in a call to function 'memcpy' declared here extern void * memcpy(void *, const void *, __kernel_size_t) __nocapture(2); ^~~~~~
I have concluded that gcc was technically right in the first place:
vchiq_complete_bulk is an externally visible function that calls free_pagelist(), which in turn derives a pointer from the global g_fragments_base variable.
g_fragments_base is initialized in vchiq_platform_init(), but we only get there if of_property_read_u32() successfully reads the cache line size. When CONFIG_OF is disabled, this always fails, and g_fragments_base is guaranteed to be NULL when vchiq_complete_bulk() gets called.
This adds a CONFIG_OF Kconfig dependency, which is also technically correct but nonobvious, and thus seems like a good fit for the warning.
Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- drivers/staging/vc04_services/Kconfig | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/staging/vc04_services/Kconfig b/drivers/staging/vc04_services/Kconfig index e61e4ca064a8..74094fff4367 100644 --- a/drivers/staging/vc04_services/Kconfig +++ b/drivers/staging/vc04_services/Kconfig @@ -1,6 +1,7 @@ config BCM2835_VCHIQ tristate "Videocore VCHIQ" depends on HAS_DMA + depends on OF depends on RASPBERRYPI_FIRMWARE || (COMPILE_TEST && !RASPBERRYPI_FIRMWARE) default y help -- 2.9.0
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