From 9c27847dda9cfae7c273cde62becf364f9fa9ea3 Mon Sep 17 00:00:00 2001 From: "Luis R. Rodriguez" Date: Wed, 27 May 2015 11:09:38 +0930 Subject: kernel/params: constify struct kernel_param_ops uses Most code already uses consts for the struct kernel_param_ops, sweep the kernel for the last offending stragglers. Other than include/linux/moduleparam.h and kernel/params.c all other changes were generated with the following Coccinelle SmPL patch. Merge conflicts between trees can be handled with Coccinelle. In the future git could get Coccinelle merge support to deal with patch --> fail --> grammar --> Coccinelle --> new patch conflicts automatically for us on patches where the grammar is available and the patch is of high confidence. Consider this a feature request. Test compiled on x86_64 against: * allnoconfig * allmodconfig * allyesconfig @ const_found @ identifier ops; @@ const struct kernel_param_ops ops = { }; @ const_not_found depends on !const_found @ identifier ops; @@ -struct kernel_param_ops ops = { +const struct kernel_param_ops ops = { }; Generated-by: Coccinelle SmPL Cc: Rusty Russell Cc: Junio C Hamano Cc: Andrew Morton Cc: Kees Cook Cc: Tejun Heo Cc: Ingo Molnar Cc: cocci@systeme.lip6.fr Cc: linux-kernel@vger.kernel.org Signed-off-by: Luis R. Rodriguez Signed-off-by: Rusty Russell --- net/sunrpc/auth.c | 2 +- net/sunrpc/xprtsock.c | 6 +++--- 2 files changed, 4 insertions(+), 4 deletions(-) (limited to 'net') diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c index 47f38be4155f..02f53674dc39 100644 --- a/net/sunrpc/auth.c +++ b/net/sunrpc/auth.c @@ -72,7 +72,7 @@ static int param_get_hashtbl_sz(char *buffer, const struct kernel_param *kp) #define param_check_hashtbl_sz(name, p) __param_check(name, p, unsigned int); -static struct kernel_param_ops param_ops_hashtbl_sz = { +static const struct kernel_param_ops param_ops_hashtbl_sz = { .set = param_set_hashtbl_sz, .get = param_get_hashtbl_sz, }; diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c index 66891e32c5e3..b0517287075b 100644 --- a/net/sunrpc/xprtsock.c +++ b/net/sunrpc/xprtsock.c @@ -2982,7 +2982,7 @@ static int param_set_portnr(const char *val, const struct kernel_param *kp) RPC_MAX_RESVPORT); } -static struct kernel_param_ops param_ops_portnr = { +static const struct kernel_param_ops param_ops_portnr = { .set = param_set_portnr, .get = param_get_uint, }; @@ -3001,7 +3001,7 @@ static int param_set_slot_table_size(const char *val, RPC_MAX_SLOT_TABLE); } -static struct kernel_param_ops param_ops_slot_table_size = { +static const struct kernel_param_ops param_ops_slot_table_size = { .set = param_set_slot_table_size, .get = param_get_uint, }; @@ -3017,7 +3017,7 @@ static int param_set_max_slot_table_size(const char *val, RPC_MAX_SLOT_TABLE_LIMIT); } -static struct kernel_param_ops param_ops_max_slot_table_size = { +static const struct kernel_param_ops param_ops_max_slot_table_size = { .set = param_set_max_slot_table_size, .get = param_get_uint, }; -- cgit v1.2.3 From b51d23e4e9fea6f264d39535c2a62d1f51e7ccc3 Mon Sep 17 00:00:00 2001 From: Dan Streetman Date: Wed, 17 Jun 2015 06:18:52 +0930 Subject: module: add per-module param_lock Add a "param_lock" mutex to each module, and update params.c to use the correct built-in or module mutex while locking kernel params. Remove the kparam_block_sysfs_r/w() macros, replace them with direct calls to kernel_param_[un]lock(module). The kernel param code currently uses a single mutex to protect modification of any and all kernel params. While this generally works, there is one specific problem with it; a module callback function cannot safely load another module, i.e. with request_module() or even with indirect calls such as crypto_has_alg(). If the module to be loaded has any of its params configured (e.g. with a /etc/modprobe.d/* config file), then the attempt will result in a deadlock between the first module param callback waiting for modprobe, and modprobe trying to lock the single kernel param mutex to set the new module's param. This fixes that by using per-module mutexes, so that each individual module is protected against concurrent changes in its own kernel params, but is not blocked by changes to other module params. All built-in modules continue to use the built-in mutex, since they will always be loaded at runtime and references (e.g. request_module(), crypto_has_alg()) to them will never cause load-time param changing. This also simplifies the interface used by modules to block sysfs access to their params; while there are currently functions to block and unblock sysfs param access which are split up by read and write and expect a single kernel param to be passed, their actual operation is identical and applies to all params, not just the one passed to them; they simply lock and unlock the global param mutex. They are replaced with direct calls to kernel_param_[un]lock(THIS_MODULE), which locks THIS_MODULE's param_lock, or if the module is built-in, it locks the built-in mutex. Suggested-by: Rusty Russell Signed-off-by: Dan Streetman Signed-off-by: Rusty Russell --- net/mac80211/rate.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'net') diff --git a/net/mac80211/rate.c b/net/mac80211/rate.c index d53355b011f5..8544e2eb570e 100644 --- a/net/mac80211/rate.c +++ b/net/mac80211/rate.c @@ -103,7 +103,7 @@ ieee80211_rate_control_ops_get(const char *name) const struct rate_control_ops *ops; const char *alg_name; - kparam_block_sysfs_write(ieee80211_default_rc_algo); + kernel_param_lock(THIS_MODULE); if (!name) alg_name = ieee80211_default_rc_algo; else @@ -117,7 +117,7 @@ ieee80211_rate_control_ops_get(const char *name) /* try built-in one if specific alg requested but not found */ if (!ops && strlen(CONFIG_MAC80211_RC_DEFAULT)) ops = ieee80211_try_rate_control_ops_get(CONFIG_MAC80211_RC_DEFAULT); - kparam_unblock_sysfs_write(ieee80211_default_rc_algo); + kernel_param_unlock(THIS_MODULE); return ops; } -- cgit v1.2.3