From: Andrew Lunn <andrew@lunn.ch>
To: Sergei Antonov <saproj@gmail.com>
Cc: netdev@vger.kernel.org, Jakub Kicinski <kuba@kernel.org>,
Vladimir Oltean <olteanv@gmail.com>
Subject: Re: [PATCH 2/2] net: moxa: prevent double-mapping of DMA areas
Date: Thu, 18 Aug 2022 21:27:05 +0200 [thread overview]
Message-ID: <Yv6SiQgzKSRL1Zy6@lunn.ch> (raw)
In-Reply-To: <20220818182948.931712-2-saproj@gmail.com>
On Thu, Aug 18, 2022 at 09:29:48PM +0300, Sergei Antonov wrote:
> Fix the warning poping up after bringing the link down, then up:
> ip link set dev eth0 down
> ip link set dev eth0 up
>
> WARNING: CPU: 0 PID: 55 at kernel/dma/debug.c:570 add_dma_entry+0x204/0x2ec
> DMA-API: moxart-ethernet 92000000.mac: cacheline tracking EEXIST, overlapping mappings aren't supported
> CPU: 0 PID: 55 Comm: ip Not tainted 5.19.0+ #57
> Hardware name: Generic DT based system
> unwind_backtrace from show_stack+0x10/0x14
> show_stack from dump_stack_lvl+0x34/0x44
> dump_stack_lvl from __warn+0xbc/0x1f0
> __warn from warn_slowpath_fmt+0x94/0xc8
> warn_slowpath_fmt from add_dma_entry+0x204/0x2ec
> add_dma_entry from dma_map_page_attrs+0x110/0x328
> dma_map_page_attrs from moxart_mac_open+0x134/0x320
> moxart_mac_open from __dev_open+0x11c/0x1ec
> __dev_open from __dev_change_flags+0x194/0x22c
> __dev_change_flags from dev_change_flags+0x14/0x44
> dev_change_flags from devinet_ioctl+0x6d4/0x93c
> devinet_ioctl from inet_ioctl+0x1ac/0x25c
>
> Unmap RX memory areas in moxart_mac_stop(), so that moxart_mac_open()
> will map them anew instead of double-mapping. To avoid code duplication,
> create a new function moxart_mac_unmap_rx(). Nullify unmapped pointers to
> prevent double-unmapping (ex: moxart_mac_stop(), then moxart_remove()).
This makes the code symmetric, which is good.
However, moxart_mac_free_memory() will also free the descriptors,
which is not required. moxart_remove() should undo what the probe did,
nothing more.
Andrew
next prev parent reply other threads:[~2022-08-18 19:27 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-18 18:29 [PATCH 1/2] net: moxa: do not call dma_unmap_single() with null Sergei Antonov
2022-08-18 18:29 ` [PATCH 2/2] net: moxa: prevent double-mapping of DMA areas Sergei Antonov
2022-08-18 19:27 ` Andrew Lunn [this message]
2022-08-19 8:12 ` Sergei Antonov
2022-08-19 11:00 ` Vladimir Oltean
2022-08-18 19:18 ` [PATCH 1/2] net: moxa: do not call dma_unmap_single() with null Andrew Lunn
2022-08-19 7:27 ` Sergei Antonov
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