netdev - Re: mlxsw: spectrum: Introduce ACL core with simple TCAM implementation

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Date:   Tue, 7 Feb 2017 14:13:34 +0000
From:   Colin Ian King <colin.king@...onical.com>
To:     Jiri Pirko <jiri@...lanox.com>
Cc:     Ido Schimmel <idosch@...lanox.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: mlxsw: spectrum: Introduce ACL core with simple TCAM
 implementation

Hi Jiri,

mlxsw_sp_acl_tcam_chunk_create has an issue picked up by static analysis:

 816        struct mlxsw_sp_acl_tcam_chunk *chunk;
 817        int err;
 818
    CID 1400029 (#1 of 1): Operands don't affect result
(CONSTANT_EXPRESSION_RESULT)result_independent_of_operands: priority ==
18446744073709551615UL is always false regardless of the values of its
operands. This occurs as the logical operand of "if".

 819        if (priority == MLXSW_SP_ACL_TCAM_CATCHALL_PRIO)
 820                return ERR_PTR(-EINVAL);
 821

priority is an unsigned int, where as MLXSW_SP_ACL_TCAM_CATCHALL_PRIO is
(-1UL), so the unsigned comparison to a signed long (-1UL) will never be
true. So I think this needs some reworking, especially as
MLXSW_SP_ACL_TCAM_CATCHALL_PRIO priority is being used as an unsigned
long priority in some places, and priority is an unsigned int in other
places of the code.

Colin