linux-kernel - Is netif_tx_lock() SMP PREEMPT safe?

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <200802151725.05424.mitov@issp.bas.bg>
Date:	Fri, 15 Feb 2008 17:25:05 +0200
From:	Marin Mitov <mitov@...p.bas.bg>
To:	linux-kernel@...r.kernel.org
Subject: Is netif_tx_lock() SMP PREEMPT safe?

Hi all,

As in: include/linux/netdevice.h (kernel-2.6.24.2) one finds:

static inline void __netif_tx_lock(struct net_device *dev, int cpu)
{
        spin_lock(&dev->_xmit_lock);
        dev->xmit_lock_owner = cpu;
}

static inline void netif_tx_lock(struct net_device *dev)
{
        __netif_tx_lock(dev, smp_processor_id());
}

Does netif_tx_lock(struct net_device *dev) expands into:

cpu = smp_processor_id(); 
<preempt & shift to another cpu (bogus)>
spin_lock(&dev->_xmit_lock);
dev->xmit_lock_owner = cpu; /* cpu is not the lock owner */

Or to:

spin_lock(&dev->_xmit_lock);
dev->xmit_lock_owner = smp_processor_id();

which is correct?

Thanks in advance for your answer.

Regards

Marin Mitov

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/