From: Edward Cree <ecree@solarflare•com>
To: David Laight <David.Laight@ACULAB•COM>
Cc: 'Shradha Shah' <sshah@solarflare•com>,
David Miller <davem@davemloft•net>,
"netdev@vger•kernel.org" <netdev@vger•kernel.org>,
"linux-net-drivers@solarflare•com"
<linux-net-drivers@solarflare•com>
Subject: Re: [PATCH net-next 02/14] sfc: Add sysfs entry for flags (link control and primary)
Date: Fri, 29 May 2015 14:09:01 +0100 [thread overview]
Message-ID: <556864ED.1080408@solarflare.com> (raw)
In-Reply-To: <063D6719AE5E284EB5DD2968C1650D6D1CB42986@AcuExch.aculab.com>
On 29/05/15 11:48, David Laight wrote:
> From: Shradha Shah
>> Sent: 29 May 2015 11:01
>> On every adapter there will be one primary PF per adaptor and
>> one link control PF per port.
> ...
>> + return sprintf(buf, "%d\n",
>> + ((efx->mcdi->fn_flags) &
>> + (1 << MC_CMD_DRV_ATTACH_EXT_OUT_FLAG_LINKCTRL))
>> + ? 1 : 0);
> Horrid expression.
> Why not:
> (efx->mcdi->fn_flags >> MC_CMD_DRV_ATTACH_EXT_OUT_FLAG_LINKCTRL) & 1
I think the idea is that this is more explicit about what it's doing.
It's a toss-up which is more readable / idiomatic; I prefer the OP version.
(They probably compile to the same thing, though I haven't checked.)
> using sprintf() is also excessive. Maybe:
> *buf = '0' + (expression);
> return 1;
That loses the '\n'; it's annoying when you cat a file and it doesn't end in a '\n', because it gloms onto your shell prompt.
sprintf isn't really that expensive, this isn't likely to be called very frequently.
> You may also need to check for buffer overrun.
In fact Documentation/filesystems/sysfs.txt says that "show() should always use scnprintf()" and that "The buffer will always be PAGE_SIZE bytes in length."
So if we want to be consistent, it should be
return scnprintf(buf, PAGE_SIZE, "%d\n", expression);
although it'd be rather surprising if either 0\n or 1\n were ever too big for PAGE_SIZE :grin:.
next prev parent reply other threads:[~2015-05-29 13:09 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-29 9:59 [PATCH net-next 00/14] sfc: ndo_get_phys_port_id, vadaptor stats and PF unload when Vf's assigned to guest Shradha Shah
2015-05-29 10:01 ` [PATCH net-next 01/14] sfc: Add sysfs entry for physical port Shradha Shah
2015-06-01 0:32 ` David Miller
2015-05-29 10:01 ` [PATCH net-next 02/14] sfc: Add sysfs entry for flags (link control and primary) Shradha Shah
2015-05-29 10:48 ` David Laight
2015-05-29 13:09 ` Edward Cree [this message]
2015-05-29 10:01 ` [PATCH net-next 03/14] sfc: Implement ndo_gets_phys_port_id() for EF10 VFs Shradha Shah
2015-05-29 10:01 ` [PATCH net-next 04/14] sfc: add "port_" prefix to MAC stats Shradha Shah
2015-05-29 10:01 ` [PATCH net-next 05/14] sfc: set the port-id when calling MC_CMD_MAC_STATS Shradha Shah
2015-05-29 10:02 ` [PATCH net-next 06/14] sfc: display vadaptor statistics for all interfaces Shradha Shah
2015-05-29 10:02 ` [PATCH net-next 07/14] sfc: DMA the VF stats only when requested Shradha Shah
2015-05-29 10:02 ` [PATCH net-next 08/14] sfc: update netdevice statistics to use vadaptor stats Shradha Shah
2015-05-29 10:02 ` [PATCH net-next 09/14] sfc: suppress ENOENT error messages from MC_CMD_MAC_STATS Shradha Shah
2015-05-29 10:03 ` [PATCH net-next 11/14] sfc: don't update stats on VF when called in atomic context Shradha Shah
2015-05-29 10:03 ` [PATCH net-next 12/14] sfc: do not allow VFs to be destroyed if assigned to guests Shradha Shah
2015-05-29 10:03 ` [PATCH net-next 13/14] sfc: force removal of VF and vport on driver removal Shradha Shah
2015-05-29 10:03 ` [PATCH net-next 14/14] sfc: leak vports if a VF is assigned during PF unload Shradha Shah
2015-05-29 10:08 ` [PATCH net-next 10/14] sfc: suppress vadaptor stats when EVB is not present Shradha Shah
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