From 8c87df457cb58fe75b9b893007917cf8095660a0 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Tue, 22 Sep 2009 16:43:52 -0700 Subject: [PATCH] BUILD_BUG_ON(): fix it and a couple of bogus uses of it gcc permitting variable length arrays makes the current construct used for BUILD_BUG_ON() useless, as that doesn't produce any diagnostic if the controlling expression isn't really constant. Instead, this patch makes it so that a bit field gets used here. Consequently, those uses where the condition isn't really constant now also need fixing. Note that in the gfp.h, kmemcheck.h, and virtio_config.h cases MAYBE_BUILD_BUG_ON() really just serves documentation purposes - even if the expression is compile time constant (__builtin_constant_p() yields true), the array is still deemed of variable length by gcc, and hence the whole expression doesn't have the intended effect. [akpm@linux-foundation.org: make arch/sparc/include/asm/vio.h compile] [akpm@linux-foundation.org: more nonsensical assertions in tpm.c..] Signed-off-by: Jan Beulich Cc: Andi Kleen Cc: Rusty Russell Cc: Catalin Marinas Cc: "David S. Miller" Cc: Rajiv Andrade Cc: Mimi Zohar Cc: James Morris Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/sparc/include/asm/vio.h | 2 +- drivers/char/tpm/tpm.c | 4 ++-- drivers/net/niu.c | 2 +- include/linux/gfp.h | 2 +- include/linux/kernel.h | 8 ++++++-- include/linux/kmemcheck.h | 2 +- include/linux/virtio_config.h | 3 +-- 7 files changed, 13 insertions(+), 10 deletions(-) diff --git a/arch/sparc/include/asm/vio.h b/arch/sparc/include/asm/vio.h index d4de32f..6cdbf7e 100644 --- a/arch/sparc/include/asm/vio.h +++ b/arch/sparc/include/asm/vio.h @@ -258,7 +258,7 @@ static inline void *vio_dring_entry(struct vio_dring_state *dr, static inline u32 vio_dring_avail(struct vio_dring_state *dr, unsigned int ring_size) { - BUILD_BUG_ON(!is_power_of_2(ring_size)); + MAYBE_BUILD_BUG_ON(!is_power_of_2(ring_size)); return (dr->pending - ((dr->prod - dr->cons) & (ring_size - 1))); diff --git a/drivers/char/tpm/tpm.c b/drivers/char/tpm/tpm.c index b0603b2..32b957e 100644 --- a/drivers/char/tpm/tpm.c +++ b/drivers/char/tpm/tpm.c @@ -696,7 +696,7 @@ int __tpm_pcr_read(struct tpm_chip *chip, int pcr_idx, u8 *res_buf) cmd.header.in = pcrread_header; cmd.params.pcrread_in.pcr_idx = cpu_to_be32(pcr_idx); - BUILD_BUG_ON(cmd.header.in.length > READ_PCR_RESULT_SIZE); + BUG_ON(cmd.header.in.length > READ_PCR_RESULT_SIZE); rc = transmit_cmd(chip, &cmd, cmd.header.in.length, "attempting to read a pcr value"); @@ -760,7 +760,7 @@ int tpm_pcr_extend(u32 chip_num, int pcr_idx, const u8 *hash) return -ENODEV; cmd.header.in = pcrextend_header; - BUILD_BUG_ON(be32_to_cpu(cmd.header.in.length) > EXTEND_PCR_SIZE); + BUG_ON(be32_to_cpu(cmd.header.in.length) > EXTEND_PCR_SIZE); cmd.params.pcrextend_in.pcr_idx = cpu_to_be32(pcr_idx); memcpy(cmd.params.pcrextend_in.hash, hash, TPM_DIGEST_SIZE); rc = transmit_cmd(chip, &cmd, cmd.header.in.length, diff --git a/drivers/net/niu.c b/drivers/net/niu.c index 76cc261..f9364d0 100644 --- a/drivers/net/niu.c +++ b/drivers/net/niu.c @@ -5615,7 +5615,7 @@ static void niu_init_tx_mac(struct niu *np) /* The XMAC_MIN register only accepts values for TX min which * have the low 3 bits cleared. */ - BUILD_BUG_ON(min & 0x7); + BUG_ON(min & 0x7); if (np->flags & NIU_FLAGS_XMAC) niu_init_tx_xmac(np, min, max); diff --git a/include/linux/gfp.h b/include/linux/gfp.h index f53e9b8..557bdad 100644 --- a/include/linux/gfp.h +++ b/include/linux/gfp.h @@ -220,7 +220,7 @@ static inline enum zone_type gfp_zone(gfp_t flags) ((1 << ZONES_SHIFT) - 1); if (__builtin_constant_p(bit)) - BUILD_BUG_ON((GFP_ZONE_BAD >> bit) & 1); + MAYBE_BUILD_BUG_ON((GFP_ZONE_BAD >> bit) & 1); else { #ifdef CONFIG_DEBUG_VM BUG_ON((GFP_ZONE_BAD >> bit) & 1); diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 55723af..63dcaec 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -678,13 +678,17 @@ struct sysinfo { }; /* Force a compilation error if condition is true */ -#define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)])) +#define BUILD_BUG_ON(condition) ((void)BUILD_BUG_ON_ZERO(condition)) + +/* Force a compilation error if condition is constant and true */ +#define MAYBE_BUILD_BUG_ON(cond) ((void)sizeof(char[1 - 2 * !!(cond)])) /* Force a compilation error if condition is true, but also produce a result (of value 0 and type size_t), so the expression can be used e.g. in a structure initializer (or where-ever else comma expressions aren't permitted). */ -#define BUILD_BUG_ON_ZERO(e) (sizeof(char[1 - 2 * !!(e)]) - 1) +#define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); })) +#define BUILD_BUG_ON_NULL(e) ((void *)sizeof(struct { int:-!!(e); })) /* Trap pasters of __FUNCTION__ at compile-time */ #define __FUNCTION__ (__func__) diff --git a/include/linux/kmemcheck.h b/include/linux/kmemcheck.h index 136cdcd..e880d4cf9 100644 --- a/include/linux/kmemcheck.h +++ b/include/linux/kmemcheck.h @@ -152,7 +152,7 @@ static inline bool kmemcheck_is_obj_initialized(unsigned long addr, size_t size) \ _n = (long) &((ptr)->name##_end) \ - (long) &((ptr)->name##_begin); \ - BUILD_BUG_ON(_n < 0); \ + MAYBE_BUILD_BUG_ON(_n < 0); \ \ kmemcheck_mark_initialized(&((ptr)->name##_begin), _n); \ } while (0) diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h index e547e3c..0093dd7 100644 --- a/include/linux/virtio_config.h +++ b/include/linux/virtio_config.h @@ -109,8 +109,7 @@ static inline bool virtio_has_feature(const struct virtio_device *vdev, unsigned int fbit) { /* Did you forget to fix assumptions on max features? */ - if (__builtin_constant_p(fbit)) - BUILD_BUG_ON(fbit >= 32); + MAYBE_BUILD_BUG_ON(fbit >= 32); if (fbit < VIRTIO_TRANSPORT_F_START) virtio_check_driver_offered_feature(vdev, fbit); -- 2.7.4