From: Dimitris Michailidis <dm@chelsio•com>
To: Alexander Duyck <alexander.h.duyck@intel•com>
Cc: davem@davemloft•net, jeffrey.t.kirsher@intel•com,
bhutchings@solarflare•com, netdev@vger•kernel.org
Subject: Re: [ethtool PATCH 4/4] v5 Add RX packet classification interface
Date: Tue, 03 May 2011 16:23:39 -0700 [thread overview]
Message-ID: <4DC08E7B.7070906@chelsio.com> (raw)
In-Reply-To: <20110503161226.29251.40838.stgit@gitlad.jf.intel.com>
On 05/03/2011 09:12 AM, Alexander Duyck wrote:
[...]
> +static int rmgr_add(struct ethtool_rx_flow_spec *fsp)
> +{
> + __u32 loc = fsp->location;
Unneeded assignment. Couple lines later you assign a new value to loc.
> + __u32 slot_num;
> +
> + /* start at the end of the list since it is lowest priority */
> + loc = rmgr.size - 1;
> +
> + /* locate the first slot a rule can be placed in */
> + slot_num = loc / BITS_PER_LONG;
> +
> + /*
> + * Avoid testing individual bits by inverting the word and checking
> + * to see if any bits are left set, if so there are empty spots. By
> + * moving 1 + loc % BITS_PER_LONG we align ourselves to the last bit
> + * in the previous word.
> + *
> + * If loc rolls over it should be greater than or equal to rmgr.size
> + * and as such we know we have reached the end of the list.
> + */
> + if (!~(rmgr.slot[slot_num] | (~1UL << rmgr.size % BITS_PER_LONG))) {
> + loc -= 1 + (loc % BITS_PER_LONG);
> + slot_num--;
> + }
> +
> + /*
> + * Now that we are aligned with the last bit in each long we can just
> + * go though and eliminate all the longs with no free bits
> + */
> + while (loc < rmgr.size && !~(rmgr.slot[slot_num])) {
> + loc -= BITS_PER_LONG;
> + slot_num--;
> + }
> +
> + /*
> + * If we still are inside the range, test individual bits as one is
> + * likely available for our use.
> + */
> + while (loc < rmgr.size && test_bit(loc, rmgr.slot))
> + loc--;
> +
> + /* location found, insert rule */
> + if (loc < rmgr.size) {
> + fsp->location = loc;
> + return rmgr_ins(loc);
> + }
> +
> + /* No space to add this rule */
> + fprintf(stderr, "rmgr: Cannot find appropriate slot to insert rule\n");
> +
> + return -1;
> +}
[...]
> +int rxclass_rule_ins(int fd, struct ifreq *ifr,
> + struct ethtool_rx_flow_spec *fsp)
> +{
> + struct ethtool_rxnfc nfccmd;
> + __u32 loc = fsp->location;
> + int err;
> +
> + /*
> + * if location is unspecified pull rules from device
> + * and allocate a free rule for our use
> + */
> + if (loc == RX_CLS_LOC_UNSPEC) {
> + /* init table of available rules */
> + err = rmgr_init(fd, ifr);
> + if (err < 0)
> + return err;
> +
> + /* verify rule location */
> + err = rmgr_add(fsp);
> + if (err < 0)
> + return err;
> +
> + /* cleanup table and free resources */
> + rmgr_cleanup();
> + }
This logic where ethtool tries to select a filter slot when a user provides
RX_CLS_LOC_UNSPEC does not work in general. It assumes that all slots are
equal and a new filter can go into any available slot. But a device may have
restrictions on where a filter may go that ethtool doesn't know. I
mentioned during a previous review that for cxgb4 some filters require a
slot number that is a multiple of 4. There are some other constraints as
well depending on the type of filter being added. For such a device ethtool
doesn't know enough to handle RX_CLS_LOC_UNSPEC correctly.
I think RX_CLS_LOC_UNSPEC should be passed to the driver, where there is
enough knowledge to pick an appropriate slot. So I'd remove the
if (loc == RX_CLS_LOC_UNSPEC)
block above, let the driver pick a slot, and then pass the selected location
back for ethtool to report.
next prev parent reply other threads:[~2011-05-03 23:23 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-03 16:12 [ethtool PATCH 0/4] Add support for network flow classifier Alexander Duyck
2011-05-03 16:12 ` [ethtool PATCH 1/4] ethtool: remove strings based approach for displaying n-tuple Alexander Duyck
2011-05-03 16:12 ` [ethtool PATCH 2/4] Cleanup defines and header includes to address several issues Alexander Duyck
2011-05-03 16:12 ` [ethtool PATCH 3/4] Add support for __be64 and bitops, centralize several needed macros Alexander Duyck
2011-05-03 16:12 ` [ethtool PATCH 4/4] v5 Add RX packet classification interface Alexander Duyck
2011-05-03 23:23 ` Dimitris Michailidis [this message]
2011-05-03 23:34 ` Ben Hutchings
2011-05-04 0:29 ` Alexander Duyck
2011-05-04 1:35 ` Dimitris Michailidis
2011-05-04 3:10 ` Alexander Duyck
2011-05-04 17:09 ` Dimitris Michailidis
2011-05-04 17:24 ` Ben Hutchings
2011-05-04 17:33 ` Dimitris Michailidis
2011-05-04 17:41 ` Alexander Duyck
2011-05-04 18:05 ` Ben Hutchings
2011-05-04 18:21 ` Alexander Duyck
2011-05-04 18:45 ` Ben Hutchings
2011-05-04 21:07 ` Alexander Duyck
2011-05-04 21:54 ` Ben Hutchings
2011-05-04 19:06 ` Dimitris Michailidis
2011-05-04 18:18 ` Dimitris Michailidis
2011-05-04 18:35 ` Alexander Duyck
2011-05-04 18:50 ` Dimitris Michailidis
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