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Commit e4a2b36b authored by Jeff Hugo's avatar Jeff Hugo
Browse files

msm: smem: add smem_get_free_space() 



The smem_get_free_space() API is a private helper function to optimize the
SMD client's table scanning usecase.

Change-Id: I00b12bf3b667001f973fd5126278536b47e052f4
Signed-off-by: default avatarJeffrey Hugo <jhugo@codeaurora.org>
parent e76e482e

arch/arm/mach-msm/smem.c

+41 −0
Original line number Diff line number Diff line
@@ -856,6 +856,47 @@ remote_spinlock_t *smem_get_remote_spinlock(void) 
}

EXPORT_SYMBOL(smem_get_remote_spinlock);



/**

 * smem_get_free_space() - Get the available allocation free space for a

 *				partition

 *

 * @to_proc: remote SMEM host.  Determines the applicable partition

 * @returns: size in bytes available to allocate

 *

 * Helper function for SMD so that SMD only scans the channel allocation

 * table for a partition when it is reasonably certain that a channel has

 * actually been created, because scanning can be expensive.  Creating a channel

 * will consume some of the free space in a partition, so SMD can compare the

 * last free space size against the current free space size to determine if

 * a channel may have been created.  SMD can't do this directly, because the

 * necessary partition internals are restricted to just SMEM.

 */

unsigned smem_get_free_space(unsigned to_proc)

{

	struct smem_partition_header *hdr;

	struct smem_shared *shared;



	if (to_proc >= NUM_SMEM_SUBSYSTEMS) {

		pr_err("%s: invalid to_proc:%d\n", __func__, to_proc);

		return UINT_MAX;

	}



	if (partitions[to_proc].offset) {

		if (unlikely(OVERFLOW_ADD_UNSIGNED(uintptr_t,

					(uintptr_t)smem_areas[0].virt_addr,

					partitions[to_proc].offset))) {

			pr_err("%s: unexpected overflow detected\n", __func__);

			return UINT_MAX;

		}

		hdr = smem_areas[0].virt_addr + partitions[to_proc].offset;

		return hdr->offset_free_cached - hdr->offset_free_uncached;

	} else {

		shared = (void *)MSM_SHARED_RAM_BASE;

		return shared->heap_info.heap_remaining;

	}

}

EXPORT_SYMBOL(smem_get_free_space);



/**

 * init_smem_remote_spinlock - Reentrant remote spinlock initialization

 *

arch/arm/mach-msm/smem_private.h

+17 −0
Original line number Diff line number Diff line
@@ -76,4 +76,21 @@ int smem_module_init_notifier_register(struct notifier_block *nb); 
 * @nb: Notifier block to be unregistered

 */

int smem_module_init_notifier_unregister(struct notifier_block *nb);



/**

 * smem_get_free_space() - Get the available allocation free space for a

 *				partition

 *

 * @to_proc: remote SMEM host.  Determines the applicable partition

 * @returns: size in bytes available to allocate

 *

 * Helper function for SMD so that SMD only scans the channel allocation

 * table for a partition when it is reasonably certain that a channel has

 * actually been created, because scanning can be expensive.  Creating a channel

 * will consume some of the free space in a partition, so SMD can compare the

 * last free space size against the current free space size to determine if

 * a channel may have been created.  SMD can't do this directly, because the

 * necessary partition internals are restricted to just SMEM.

 */

unsigned smem_get_free_space(unsigned to_proc);

#endif /* _ARCH_ARM_MACH_MSM_SMEM_PRIVATE_H_ */