linux-kernel - Re: [PATCH] NFC: Driver for Inside Secure MicroRead NFC chip

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

Date:	Fri, 18 Mar 2011 15:12:19 +0000
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	<Waldemar.Rymarkiewicz@...to.com>
Cc:	<linux-i2c@...r.kernel.org>, <arnd@...db.de>,
	<sameo@...ux.intel.com>, <linux-kernel@...r.kernel.org>,
	<hthebaud@...idefr.com>, <matti.j.aaltonen@...ia.com>
Subject: Re: [PATCH] NFC: Driver for Inside Secure MicroRead NFC chip

> >Would it not be lighter to use atomic bit ops ?
> 
> Do you mean  in order to remove rx_mutex? 
> 
> mutex_lock(&info->rx_mutex);
> atomic_set(info->irq_state ,1);
> mutex_unlock(&info->rx_mutex);
> 
> looks a bit strange. I still need the rx_mutex to protect irq_state while reading i2c.
> 
> 	mutex_lock(&info->rx_mutex);
> 	ret = i2c_master_recv(client, info->buf, info->buflen);
> 	info->irq_state = 0;
> 	mutex_unlock(&info->rx_mutex);
> 

I was thinking clear_bit/test_and_set_bit rather than atomic_t operations.

ie in the IRQ

	clear_bit(0, &info->irq_state);


in the main path

	if (test_and_set_bit(0, &info->state))
		i2c_master_recv(...)

but if the mutex is needed anyway it doesn't help make the code saner.
--
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/