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From: "Burakov, Anatoly" <anatoly.burakov@intel.com>
To: Olivier Matz <olivier.matz@6wind.com>, dev@dpdk.org
Cc: Andrew Rybchenko <arybchenko@solarflare.com>, stable@dpdk.org
Subject: Re: [dpdk-stable] [PATCH] mempool: fix mempool virt populate with small chunks
Date: Thu, 9 Jan 2020 13:52:41 +0000
Message-ID: <8b59b3c9-ac1a-f448-e38d-063a6cb8ba7a@intel.com> (raw)
In-Reply-To: <20200109132720.15664-1-olivier.matz@6wind.com>

On 09-Jan-20 1:27 PM, Olivier Matz wrote:
> To populate a mempool with a virtual area, the mempool code calls
> rte_mempool_populate_iova() for each iova-contiguous area. It happens
> (rarely) that this area is too small to store one object. In this case,
> rte_mempool_populate_iova() returns an error, which is forwarded by
> rte_mempool_populate_virt().
> 
> This case should not throw an error in
> rte_mempool_populate_virt(). Instead, the area that is too small should
> just be ignored.
> 
> To fix this issue, change the return value of
> rte_mempool_populate_iova() to -ENOBUFS when no object can be populated,
> so it can be ignored by the caller. As this would be an API change, add
> a compat wrapper to keep the current API unchanged. The wrapper will be
> removed for 20.11.
> 
> Fixes: 354788b60cfd ("mempool: allow populating with unaligned virtual area")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
> ---
> 

The approach fixes the issue on my end, so

Tested-by: Anatoly Burakov <anatoly.burakov@intel.com>

> Is there a simple way to ensure that we won't forget to remove the
> wrapper for 20.11? Anatoly suggested me to use versioned symbols, but
> it's not clear to me how.
> 

Yes, i'd like to do better than "ah shur we won't forget pinky swear".

Can't we do this with ABI versioning? E.g.

rte_populate_iova_v20() ... returns EINVAL

rte_populate_iova_v21() ... returns ENOBUFS

I'm pretty sure, even if it doesn't break, it will still be more likely 
to not be forgotten because there's almost a guarantee that someone will 
grep for symbol versioning macros across the codebase around 20.11 
timeframe.

-- 
Thanks,
Anatoly

  parent reply	other threads:[~2020-01-09 13:52 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-09 13:27 Olivier Matz
2020-01-09 13:40 ` [dpdk-stable] [dpdk-dev] " David Marchand
2020-01-09 13:46   ` Olivier Matz
2020-01-09 13:52 ` Burakov, Anatoly [this message]
2020-01-09 14:23   ` [dpdk-stable] " Olivier Matz
2020-01-09 14:29     ` Burakov, Anatoly
2020-01-09 14:58       ` [dpdk-stable] [dpdk-dev] " Bruce Richardson
2020-01-17 14:57 ` [dpdk-stable] [PATCH v2 0/3] " Olivier Matz
2020-01-17 14:57   ` [dpdk-stable] [PATCH v2 1/3] " Olivier Matz
2020-01-17 14:57   ` [dpdk-stable] [PATCH v2 2/3] doc: announce API change for mempool IOVA populate Olivier Matz
2020-01-17 20:32     ` David Marchand
2020-01-17 14:57   ` [dpdk-stable] [PATCH v2 3/3] [20.05] mempool: return 0 if area is too small on populate Olivier Matz
2020-01-17 20:32     ` David Marchand
2020-01-20 12:02   ` [dpdk-stable] [dpdk-dev] [PATCH v2 0/3] mempool: fix mempool virt populate with small chunks Thomas Monjalon

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