Re: [PATCH rdma-core 1/4] pyverbs: Add memory allocation class

[Jason Gunthorpe <jgg@mellanox.com>]

On Thu, Nov 14, 2019 at 09:37:45AM +0000, Noa Osherovich wrote:
> From: Edward Srouji <edwards@mellanox.com>
> 
> Add new MemAlloc class which wraps some C memory allocation functions
> such as aligned_alloc, malloc and free.
> This allows Pyverbs' users to easily allocate and free memory in C
> style, i.e when the memory address must be passed to a driver API.
> 
> Signed-off-by: Edward Srouji <edwards@mellanox.com>
> Reviewd-by: Daria Velikovsky <daria@mellanox.com>
> Reviewd-by: Noa Osherovich <noaos@mellanox.com>
>  pyverbs/base.pxd |  3 +++
>  pyverbs/base.pyx | 26 ++++++++++++++++++++++++++
>  2 files changed, 29 insertions(+)
> 
> diff --git a/pyverbs/base.pxd b/pyverbs/base.pxd
> index e85f7c020e1c..e956a79915ff 100644
> +++ b/pyverbs/base.pxd
> @@ -9,3 +9,6 @@ cdef class PyverbsObject(object):
>  
>  cdef class PyverbsCM(PyverbsObject):
>      cpdef close(self)
> +
> +cdef class MemAlloc(object):
> +   pass
> diff --git a/pyverbs/base.pyx b/pyverbs/base.pyx
> index 8b3e6741ae19..a41cfc748ad0 100644
> +++ b/pyverbs/base.pyx
> @@ -3,8 +3,14 @@
>  
>  import logging
>  from pyverbs.pyverbs_error import PyverbsRDMAError
> +from libc.stdlib cimport malloc, free
> +from libc.stdint cimport uintptr_t
>  from libc.errno cimport errno
>  
> +cdef extern from 'stdlib.h':
> +    void *aligned_alloc(size_t alignment, size_t size)

posix_memalign() is the correct function to use, and a cdef for it is
already in posix.stdlib

> +cdef class MemAlloc(object):
> +    @staticmethod
> +    def malloc(size):
> +        ptr = malloc(size)
> +        if not ptr:
> +            raise MemoryError('Failed to allocate memory')
> +        return <uintptr_t>ptr
> +
> +    @staticmethod
> +    def aligned_alloc(size, alignment=8):
> +        ptr = aligned_alloc(alignment, size)
> +        if not ptr:
> +            raise MemoryError('Failed to allocate memory')
> +        return <uintptr_t>ptr
> +
> +    @staticmethod
> +    def free(ptr):
> +        free(<void*><uintptr_t>ptr)

Why is this in a class?

Jason