From: Andi Kleen <andi@firstfloor.org>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Andi Kleen <andi@firstfloor.org>,
linux-kernel@vger.kernel.org, ebiederm@xmission.com
Subject: Re: [PATCH] [1/11] Add rcustring ADT for RCU protected strings
Date: Tue, 22 Dec 2009 11:05:53 +0100 [thread overview]
Message-ID: <20091222100553.GA10314@basil.fritz.box> (raw)
In-Reply-To: <20091222024635.GA9279@linux.vnet.ibm.com>
On Mon, Dec 21, 2009 at 06:46:35PM -0800, Paul E. McKenney wrote:
> My guess is that you will sooner or later need a size field, perhaps
> under some debug config parameter.
That can be gotten from ksize() if needed.
> > +/*
> > + * 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(const char *str, int size, gfp_t gfp)
> > +{
> > + char *copy = kmalloc(size, gfp);
> > + if (!str)
> > + return NULL;
>
> Assuming that "str" points to the "str" field of a struct rcu_string,
> what prevents a grace period from elapsing at this point, freeing the
> "str" out from under us?
Yes, that's broken thanks. I'll move the reference into the read lock
section.
-Andi
--
ak@linux.intel.com -- Speaking for myself only.
next prev parent reply other threads:[~2009-12-22 10:05 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-21 1:20 [PATCH] [0/11] SYSCTL: Use RCU to avoid races with string sysctls Andi Kleen
2009-12-21 1:20 ` [PATCH] [1/11] Add rcustring ADT for RCU protected strings Andi Kleen
2009-12-22 2:46 ` Paul E. McKenney
2009-12-22 10:05 ` Andi Kleen [this message]
2009-12-22 20:59 ` Paul E. McKenney
2009-12-21 1:20 ` [PATCH] [2/11] Add a kernel_address() that works for data too Andi Kleen
2009-12-21 1:20 ` [PATCH] [3/11] SYSCTL: Add proc_rcu_string to manage sysctls using rcu strings Andi Kleen
2009-12-22 2:51 ` Paul E. McKenney
2009-12-22 3:00 ` Eric W. Biederman
2009-12-22 7:44 ` Paul E. McKenney
2009-12-21 1:20 ` [PATCH] [4/11] SYSCTL: Use RCU strings for core_pattern sysctl Andi Kleen
2009-12-21 1:20 ` [PATCH] [5/11] SYSCTL: Add call_usermodehelper_cleanup() Andi Kleen
2009-12-21 1:20 ` [PATCH] [6/11] SYSCTL: Convert modprobe_path to proc_rcu_string() Andi Kleen
2009-12-21 1:20 ` [PATCH] [7/11] SYSCTL: Convert poweroff_command to proc_rcu_string Andi Kleen
2009-12-21 1:20 ` [PATCH] [8/11] SYSCTL: Convert hotplug helper string to proc_rcu_string() Andi Kleen
2009-12-22 19:03 ` Greg KH
2009-12-21 1:20 ` [PATCH] [9/11] SYSCTL: Add a mutex to the page_alloc zone order sysctl Andi Kleen
2009-12-21 1:20 ` [PATCH] [10/11] SYSCTL: Use RCU protected sysctl for ocfs group add helper Andi Kleen
2009-12-21 1:20 ` [PATCH] [11/11] SYSCTL: Convert IRDA text sysctl to RCU Andi Kleen
2009-12-21 1:59 ` [PATCH] [0/11] SYSCTL: Use RCU to avoid races with string sysctls Eric W. Biederman
2009-12-21 2:04 ` Andi Kleen
2009-12-21 2:31 ` Eric W. Biederman
2009-12-21 3:21 ` Andi Kleen
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