From: Thomas Monjalon <thomas@monjalon.net>
To: "Bruce Richardson" <bruce.richardson@intel.com>,
"Morten Brørup" <mb@smartsharesystems.com>
Cc: dev@dpdk.org, Tyler Retzlaff <roretzla@linux.microsoft.com>,
Ferruh Yigit <ferruh.yigit@amd.com>,
Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>,
Ajit Khaparde <ajit.khaparde@broadcom.com>,
Somnath Kotur <somnath.kotur@broadcom.com>,
Gaetan Rivet <grive@u256.net>, Jie Hai <haijie1@huawei.com>,
Long Li <longli@microsoft.com>, Wei Hu <weh@microsoft.com>
Subject: Re: [PATCH 2/2] drivers/net: support single queue per port
Date: Wed, 06 Nov 2024 17:06:45 +0100 [thread overview]
Message-ID: <5956521.peFUeoqG7q@thomas> (raw)
In-Reply-To: <98CBD80474FA8B44BF855DF32C47DC35E9F88A@smartserver.smartshare.dk>
06/11/2024 13:19, Morten Brørup:
> > From: Bruce Richardson [mailto:bruce.richardson@intel.com]
> > Sent: Wednesday, 6 November 2024 12.52
> >
> > On Fri, Oct 25, 2024 at 11:52:23AM +0000, Morten Brørup wrote:
> > > When configuring DPDK for one queue per port
> > > (#define RTE_MAX_QUEUES_PER_PORT 1), compilation of some network
> > drivers
> > > fails with e.g.:
> > >
> > > ../drivers/net/bnxt/bnxt_rxq.c: In function 'bnxt_rx_queue_stop':
> > > ../drivers/net/bnxt/bnxt_rxq.c:587:34: error: array subscript 1 is
> > above array bounds of 'uint8_t[1]' {aka 'unsigned char[1]'} [-
> > Werror=array-bounds=]
> > > 587 | dev->data->rx_queue_state[q_id] =
> > RTE_ETH_QUEUE_STATE_STOPPED;
> > > | ~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~
> > > In file included from ../drivers/net/bnxt/bnxt.h:16,
> > > from ../drivers/net/bnxt/bnxt_rxq.c:10:
> > > ../lib/ethdev/ethdev_driver.h:168:17: note: while referencing
> > 'rx_queue_state'
> > > 168 | uint8_t rx_queue_state[RTE_MAX_QUEUES_PER_PORT];
> > > | ^~~~~~~~~~~~~~
> > >
> > > To fix this, a hint is added to the network drivers where a compiler
> > in
> > > the CI has been seen to emit the above error when DPDK is configured
> > for
> > > one queue per port, but we know that the error cannot occur.
[...]
> > > for (i = 0; i < dev->data->nb_rx_queues; i++) {
> > > + __rte_assume(i < RTE_MAX_QUEUES_PER_PORT);
> > > rxq = dev->data->rx_queues[i];
[...]
> > BTW: is this the only/best way to put in the assumption? If it were me,
> > I'd
> > look to put before the loop the underlying assumption that
> > (dev->data->nb_XX_queues < RTE_MAX_QUEUES_PER_PORT), rather than
> > putting
> > the assumption on "i".
>
> I would also prefer putting it outside the loop,
> but it doesn't work in cases where the variable
> is potentially modified inside the loop.
> And here's the problem with that:
> Passing it as a parameter to a logging macro
> makes the compiler think it is "potentially modified".
I don't understand this part.
"i" is not a pointer, so how it can be modified?
> And thus, I have to put it where it hurts, and decided to do it consistently.
Why doing something heavier consistently?
I would prefer to catch the problematic cases only with this macro.
next prev parent reply other threads:[~2024-11-06 16:06 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-25 11:52 [PATCH 0/2] ethdev: " Morten Brørup
2024-10-25 11:52 ` [PATCH 1/2] eal: add unreachable and precondition hints Morten Brørup
2024-11-04 11:40 ` Morten Brørup
2024-11-04 12:19 ` Bruce Richardson
2024-11-04 12:53 ` Morten Brørup
2024-11-06 11:48 ` Bruce Richardson
2024-10-25 11:52 ` [PATCH 2/2] drivers/net: support single queue per port Morten Brørup
2024-10-25 21:27 ` Ajit Khaparde
2024-10-25 21:56 ` Long Li
2024-11-06 11:52 ` Bruce Richardson
2024-11-06 12:19 ` Morten Brørup
2024-11-06 13:28 ` Bruce Richardson
2024-11-06 16:06 ` Thomas Monjalon [this message]
2024-11-07 10:28 ` Morten Brørup
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