----- Original Message ----- > From: "Omar Sandoval" <osan...@osandov.com> > To: "Chris Mason" <c...@fb.com>, "Josef Bacik" <jba...@fb.com>, > linux-bt...@vger.kernel.org, "Paul E. McKenney" > <paul...@linux.vnet.ibm.com>, "Josh Triplett" <j...@joshtriplett.org>, > "Steven Rostedt" <rost...@goodmis.org>, > "Mathieu Desnoyers" <mathieu.desnoy...@efficios.com>, "Lai Jiangshan" > <la...@cn.fujitsu.com>, > linux-kernel@vger.kernel.org > Sent: Thursday, September 18, 2014 5:28:11 AM > Subject: [PATCH] Move BTRFS RCU string to common library > > The RCU-friendy string API used internally by BTRFS is generic enough for > common use. This doesn't add any new functionality, but instead just moves > the > code and documents the existing API. > > Signed-off-by: Omar Sandoval <osan...@osandov.com>
[...] > --- /dev/null > +++ b/include/linux/rcustring.h > @@ -0,0 +1,84 @@ > +/* > + * RCU-friendly strings > + * > + * Copyright (C) 2012 Red Hat. All rights reserved. > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License as published by > + * the Free Software Foundation; either version 2 of the License, or > + * (at your option) any later version. > + * > + * This program is distributed in the hope that it will be useful, > + * but WITHOUT ANY WARRANTY; without even the implied warranty of > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > + * GNU General Public License for more details. > + * > + * You should have received a copy of the GNU General Public License > + * along with this program; if not, you can access it online at > + * http://www.gnu.org/licenses/gpl-2.0.html. > + */ > + > +#ifndef _LINUX_RCUSTRING_H > +#define _LINUX_RCUSTRING_H > + > +struct rcu_string { > + struct rcu_head rcu; > + char str[0]; > +}; > + > +/** > + * rcu_string_strdup() - create an RCU string from a string > + * @src: The string to copy > + * @flags: Flags for kmalloc > + */ > +static inline struct rcu_string *rcu_string_strdup(const char *src, gfp_t > flags) > +{ > + size_t len = strlen(src) + 1; > + struct rcu_string *ret = kmalloc(sizeof(struct rcu_string) + > + (len * sizeof(char)), flags); Just a nit: not sure if we want that much code within declarations ? Splitting declarations and non-trivial initial assignments might be a bit clearer in this case. > + if (!ret) > + return ret; > + memcpy(ret->str, src, len); > + return ret; > +} > + > +/** > + * rcu_string_free() - free an RCU string > + * @str: The string > + */ > +static inline void rcu_string_free(struct rcu_string *str) > +{ > + if (str) > + kfree_rcu(str, rcu); > +} > + > +/* > + * rcu_string_dereference() - dereference an RCU string > + * @str: The string > + * > + * Like rcu_dereference, this must be done in an RCU critical section. > + */ > +static inline char *rcu_string_dereference(struct rcu_string *rcu_str) > +{ > + return rcu_dereference(rcu_str)->str; > +} > + > +/** > + * printk_in_rcu() - printk in an RCU read-side critical section printk returns an integer, perhaps this macro should take it into account ? > + */ > +#define printk_in_rcu(fmt, ...) do { \ > + rcu_read_lock(); \ > + printk(fmt, __VA_ARGS__); \ > + rcu_read_unlock(); \ > +} while (0) The usual coding style for those define (using tabs to end lines): #define printk_in_rcu(fmt, ...) \ do { \ .... \ } while (0) > + > +/** > + * printk_ratelimited_in_rcu() - printk in an RCU read-side critical section Same as above: printk_ratelimit returns an integer. Thanks, Mathieu > + */ > +#define printk_ratelimited_in_rcu(fmt, ...) do { \ > + rcu_read_lock(); \ > + printk_ratelimited(fmt, __VA_ARGS__); \ > + rcu_read_unlock(); \ > +} while (0) > + > +#endif > -- > 2.1.0 > > -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
