diff options
| -rw-r--r-- | drivers/misc/vmw_vmci/vmci_driver.c | 2 | ||||
| -rw-r--r-- | include/linux/vmw_vmci_defs.h | 43 |
2 files changed, 40 insertions, 5 deletions
diff --git a/drivers/misc/vmw_vmci/vmci_driver.c b/drivers/misc/vmw_vmci/vmci_driver.c index b823f9a6e464..896be150e28f 100644 --- a/drivers/misc/vmw_vmci/vmci_driver.c +++ b/drivers/misc/vmw_vmci/vmci_driver.c @@ -113,5 +113,5 @@ module_exit(vmci_drv_exit); MODULE_AUTHOR("VMware, Inc."); MODULE_DESCRIPTION("VMware Virtual Machine Communication Interface."); -MODULE_VERSION("1.1.3.0-k"); +MODULE_VERSION("1.1.4.0-k"); MODULE_LICENSE("GPL v2"); diff --git a/include/linux/vmw_vmci_defs.h b/include/linux/vmw_vmci_defs.h index 65ac54c61c18..1bd31a38c51e 100644 --- a/include/linux/vmw_vmci_defs.h +++ b/include/linux/vmw_vmci_defs.h @@ -734,6 +734,41 @@ static inline void *vmci_event_data_payload(struct vmci_event_data *ev_data) } /* + * Helper to read a value from a head or tail pointer. For X86_32, the + * pointer is treated as a 32bit value, since the pointer value + * never exceeds a 32bit value in this case. Also, doing an + * atomic64_read on X86_32 uniprocessor systems may be implemented + * as a non locked cmpxchg8b, that may end up overwriting updates done + * by the VMCI device to the memory location. On 32bit SMP, the lock + * prefix will be used, so correctness isn't an issue, but using a + * 64bit operation still adds unnecessary overhead. + */ +static inline u64 vmci_q_read_pointer(atomic64_t *var) +{ +#if defined(CONFIG_X86_32) + return atomic_read((atomic_t *)var); +#else + return atomic64_read(var); +#endif +} + +/* + * Helper to set the value of a head or tail pointer. For X86_32, the + * pointer is treated as a 32bit value, since the pointer value + * never exceeds a 32bit value in this case. On 32bit SMP, using a + * locked cmpxchg8b adds unnecessary overhead. + */ +static inline void vmci_q_set_pointer(atomic64_t *var, + u64 new_val) +{ +#if defined(CONFIG_X86_32) + return atomic_set((atomic_t *)var, (u32)new_val); +#else + return atomic64_set(var, new_val); +#endif +} + +/* * Helper to add a given offset to a head or tail pointer. Wraps the * value of the pointer around the max size of the queue. */ @@ -741,14 +776,14 @@ static inline void vmci_qp_add_pointer(atomic64_t *var, size_t add, u64 size) { - u64 new_val = atomic64_read(var); + u64 new_val = vmci_q_read_pointer(var); if (new_val >= size - add) new_val -= size; new_val += add; - atomic64_set(var, new_val); + vmci_q_set_pointer(var, new_val); } /* @@ -758,7 +793,7 @@ static inline u64 vmci_q_header_producer_tail(const struct vmci_queue_header *q_header) { struct vmci_queue_header *qh = (struct vmci_queue_header *)q_header; - return atomic64_read(&qh->producer_tail); + return vmci_q_read_pointer(&qh->producer_tail); } /* @@ -768,7 +803,7 @@ static inline u64 vmci_q_header_consumer_head(const struct vmci_queue_header *q_header) { struct vmci_queue_header *qh = (struct vmci_queue_header *)q_header; - return atomic64_read(&qh->consumer_head); + return vmci_q_read_pointer(&qh->consumer_head); } /* |