From: Jakub Kicinski <kuba@kernel•org>
To: Shay Agroskin <shayagr@amazon•com>
Cc: Paolo Abeni <pabeni@redhat•com>,
David Miller <davem@davemloft•net>, <netdev@vger•kernel.org>,
"Woodhouse, David" <dwmw@amazon•com>,
"Machulsky, Zorik" <zorik@amazon•com>,
"Matushevsky, Alexander" <matua@amazon•com>,
Saeed Bshara <saeedb@amazon•com>, "Wilson, Matt" <msw@amazon•com>,
"Liguori, Anthony" <aliguori@amazon•com>,
"Bshara, Nafea" <nafea@amazon•com>,
"Belgazal, Netanel" <netanel@amazon•com>,
"Saidi, Ali" <alisaidi@amazon•com>,
"Herrenschmidt, Benjamin" <benh@amazon•com>,
"Kiyanovski, Arthur" <akiyano@amazon•com>,
"Dagan, Noam" <ndagan@amazon•com>,
"Arinzon, David" <darinzon@amazon•com>,
"Itzko, Shahar" <itzko@amazon•com>,
"Abboud, Osama" <osamaabb@amazon•com>,
Eric Dumazet <edumazet@google•com>,
Vladimir Oltean <vladimir.oltean@nxp•com>,
Andrew Lunn <andrew@lunn•ch>,
Guangbin Huang <huangguangbin2@huawei•com>,
Jie Wang <wangjie125@huawei•com>,
Johannes Berg <johannes@sipsolutions•net>,
Edward Cree <ecree.xilinx@gmail•com>,
Florian Westphal <fw@strlen•de>
Subject: Re: [PATCH v6 net-next 1/7] netlink: Add a macro to set policy message with format string
Date: Wed, 22 Mar 2023 11:40:41 -0700 [thread overview]
Message-ID: <20230322114041.71df75d1@kernel.org> (raw)
In-Reply-To: <pj41zlsfdxymx0.fsf@u570694869fb251.ant.amazon.com>
On Wed, 22 Mar 2023 14:39:49 +0200 Shay Agroskin wrote:
> > You should use '__extack' even above, to avoid multiple
> > evaluation of
> > the 'extack' expression.
>
> I've got to admit that I don't understand the cost of such
> evaluations. I thought that it was added to help readers of the
> source code to understand what is the type of this attribute and
> have a better warning message when the wrong variable is passed
> (kind of typing in Python which isn't strictly needed).
> What cost is there for casting a pointer ?
It's not about the cost, the macros are unfolded by the preprocessor,
in the unlikely case someone passes extack++ as an argument using it
twice inside the body of the macro will increment the value twice.
#define MACRO(arg) function_bla(arg, arg) // use arg twice
int a = 1;
MACRO(a++);
print(a); // should print 2, will print 3
next prev parent reply other threads:[~2023-03-22 18:40 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-20 13:25 [PATCH v6 net-next 0/7] Add tx push buf len param to ethtool Shay Agroskin
2023-03-20 13:25 ` [PATCH v6 net-next 1/7] netlink: Add a macro to set policy message with format string Shay Agroskin
2023-03-22 9:31 ` Paolo Abeni
2023-03-22 12:39 ` Shay Agroskin
2023-03-22 18:40 ` Jakub Kicinski [this message]
2023-03-23 16:38 ` Shay Agroskin
2023-03-23 16:54 ` Jakub Kicinski
2023-03-23 17:13 ` Shay Agroskin
2023-03-23 19:44 ` Shay Agroskin
2023-03-23 20:34 ` Jakub Kicinski
2023-03-25 13:49 ` Shay Agroskin
2023-03-27 17:33 ` Jakub Kicinski
2023-03-20 13:25 ` [PATCH v6 net-next 2/7] ethtool: Add support for configuring tx_push_buf_len Shay Agroskin
2023-03-20 13:25 ` [PATCH v6 net-next 3/7] net: ena: Make few cosmetic preparations to support large LLQ Shay Agroskin
2023-03-20 13:25 ` [PATCH v6 net-next 4/7] net: ena: Add an option to configure large LLQ headers Shay Agroskin
2023-03-20 13:25 ` [PATCH v6 net-next 5/7] net: ena: Recalculate TX state variables every device reset Shay Agroskin
2023-03-20 13:25 ` [PATCH v6 net-next 6/7] net: ena: Add support to changing tx_push_buf_len Shay Agroskin
2023-03-20 13:25 ` [PATCH v6 net-next 7/7] net: ena: Advertise TX push support Shay Agroskin
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