From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Andi Kleen <andi@firstfloor.org>
Cc: ebiederm@xmission.com, akpm@linux-foundation.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] [1/9] Add rcustring ADT for RCU protected strings v2
Date: Tue, 5 Jan 2010 06:11:46 -0800 [thread overview]
Message-ID: <20100105141146.GD6836@linux.vnet.ibm.com> (raw)
In-Reply-To: <20100105104746.GB1778@basil.fritz.box>
On Tue, Jan 05, 2010 at 11:47:46AM +0100, Andi Kleen wrote:
> On Mon, Jan 04, 2010 at 09:32:52PM -0800, Paul E. McKenney wrote:
> > > +/*
> > > + * Get a local private copy of a RCU protected string.
> > > + * Mostly useful to get a string that is stable while sleeping.
> > > + * Caller must free returned string.
> > > + */
> > > +char *access_rcu_string(char **str, int size, gfp_t gfp)
> > > +{
> > > + char *copy = kmalloc(size, gfp);
> > > + if (!str)
> > > + return NULL;
> > > + rcu_read_lock();
> > > + strlcpy(copy, rcu_dereference(*str), size);
> >
> > What if "str" is non-NULL, but "*str" is NULL? Or is that disallowed
> > somehow?
>
> I would consider it disallowed, all the strings have some default value.
> Empty string would be ""
>
> If we allowed it the caller couldn't easily distingush error from expected NULL.
OK, then:
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Thanx, Paul
next prev parent reply other threads:[~2010-01-05 14:12 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-05 2:15 [PATCH] [0/9] SYSCTL: Use RCU to avoid races with string sysctls v2 Andi Kleen
2010-01-05 2:15 ` [PATCH] [1/9] Add rcustring ADT for RCU protected strings v2 Andi Kleen
2010-01-05 5:32 ` Paul E. McKenney
2010-01-05 10:47 ` Andi Kleen
2010-01-05 14:11 ` Paul E. McKenney [this message]
2010-01-05 14:19 ` Andi Kleen
2010-01-08 23:50 ` Andrew Morton
2010-01-11 12:12 ` Bert Wesarg
2010-01-11 14:26 ` Andi Kleen
2010-01-05 2:15 ` [PATCH] [2/9] Add a kernel_address() that works for data too Andi Kleen
2010-01-05 8:44 ` Russell King
2010-01-05 8:58 ` Sam Ravnborg
2010-01-05 19:04 ` Russell King
2010-01-05 19:15 ` Andi Kleen
2010-01-08 23:51 ` Andrew Morton
2010-01-05 2:15 ` [PATCH] [3/9] SYSCTL: Add proc_rcu_string to manage sysctls using rcu strings Andi Kleen
2010-01-05 2:15 ` [PATCH] [4/9] SYSCTL: Use RCU strings for core_pattern sysctl Andi Kleen
2010-01-05 6:56 ` Eric W. Biederman
2010-01-05 11:49 ` Andi Kleen
2010-01-05 2:15 ` [PATCH] [5/9] SYSCTL: Add call_usermodehelper_cleanup() Andi Kleen
2010-01-05 2:15 ` [PATCH] [6/9] SYSCTL: Convert modprobe_path to proc_rcu_string() Andi Kleen
2010-01-05 2:15 ` [PATCH] [7/9] SYSCTL: Convert poweroff_command to proc_rcu_string Andi Kleen
2010-01-05 2:15 ` [PATCH] [8/9] SYSCTL: Convert hotplug helper string to proc_rcu_string() Andi Kleen
2010-01-05 2:15 ` [PATCH] [9/9] SYSCTL: Use RCU protected sysctl for ocfs group add helper Andi Kleen
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