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Tue, 16 May 2017 00:19:10 -0700 (PDT) Received: from ubuntu16.spreadtrum.com ([117.18.48.82]) by smtp.gmail.com with ESMTPSA id q27sm22943846pfk.4.2017.05.16.00.19.07 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 16 May 2017 00:19:10 -0700 (PDT) From: Chunyan Zhang To: rostedt@goodmis.org Cc: zhang.lyra@gmail.com, linux-kernel@vger.kernel.org Subject: [PATCH v2] trace: fix the errors caused by incompatible type of RCU variables Date: Tue, 16 May 2017 15:18:47 +0800 Message-Id: <1494919127-32603-1-git-send-email-zhang.chunyan@linaro.org> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The variables which are processed by RCU functions should be annotated as RCU, otherwise sparse will report the errors like below: "error: incompatible types in comparison expression (different address spaces)" Signed-off-by: Chunyan Zhang --- Changes in v2: * Addressed Steven's comments - Use rcu_dereference_protected() instead of rcu_dereference_raw_notrace() * Rebased on v4.12-rc1 include/linux/ftrace.h | 6 +++--- include/linux/trace_events.h | 2 +- kernel/trace/ftrace.c | 42 ++++++++++++++++++++++++++++-------------- kernel/trace/trace.h | 6 +++--- 4 files changed, 35 insertions(+), 21 deletions(-) -- 2.7.4 diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index 473f088..056395c7 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -142,8 +142,8 @@ enum { #ifdef CONFIG_DYNAMIC_FTRACE /* The hash used to know what functions callbacks trace */ struct ftrace_ops_hash { - struct ftrace_hash *notrace_hash; - struct ftrace_hash *filter_hash; + struct ftrace_hash __rcu *notrace_hash; + struct ftrace_hash __rcu *filter_hash; struct mutex regex_lock; }; @@ -165,7 +165,7 @@ static inline void ftrace_free_init_mem(void) { } */ struct ftrace_ops { ftrace_func_t func; - struct ftrace_ops *next; + struct ftrace_ops __rcu *next; unsigned long flags; void *private; ftrace_func_t saved_func; diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h index a556805..89f7bd5d 100644 --- a/include/linux/trace_events.h +++ b/include/linux/trace_events.h @@ -327,7 +327,7 @@ enum { struct trace_event_file { struct list_head list; struct trace_event_call *event_call; - struct event_filter *filter; + struct event_filter __rcu *filter; struct dentry *dir; struct trace_array *tr; struct trace_subsystem_dir *system; diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 39dca4e..116742b 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -113,7 +113,8 @@ static int ftrace_disabled __read_mostly; static DEFINE_MUTEX(ftrace_lock); -static struct ftrace_ops *ftrace_ops_list __read_mostly = &ftrace_list_end; +static struct ftrace_ops __rcu * + ftrace_ops_list __read_mostly = &ftrace_list_end; ftrace_func_t ftrace_trace_function __read_mostly = ftrace_stub; static struct ftrace_ops global_ops; @@ -169,8 +170,11 @@ int ftrace_nr_registered_ops(void) mutex_lock(&ftrace_lock); - for (ops = ftrace_ops_list; - ops != &ftrace_list_end; ops = ops->next) + for (ops = rcu_dereference_protected(ftrace_ops_list, + lockdep_is_held(&ftrace_lock)); + ops != &ftrace_list_end; + ops = rcu_dereference_protected(ops->next, + lockdep_is_held(&ftrace_lock))) cnt++; mutex_unlock(&ftrace_lock); @@ -275,10 +279,11 @@ static void update_ftrace_function(void) * If there's only one ftrace_ops registered, the ftrace_ops_list * will point to the ops we want. */ - set_function_trace_op = ftrace_ops_list; + set_function_trace_op = rcu_dereference_protected(ftrace_ops_list, + lockdep_is_held(&ftrace_lock)); /* If there's no ftrace_ops registered, just call the stub function */ - if (ftrace_ops_list == &ftrace_list_end) { + if (set_function_trace_op == &ftrace_list_end) { func = ftrace_stub; /* @@ -286,7 +291,8 @@ static void update_ftrace_function(void) * recursion safe and not dynamic and the arch supports passing ops, * then have the mcount trampoline call the function directly. */ - } else if (ftrace_ops_list->next == &ftrace_list_end) { + } else if (rcu_dereference_protected(ftrace_ops_list->next, + lockdep_is_held(&ftrace_lock)) == &ftrace_list_end) { func = ftrace_ops_get_list_func(ftrace_ops_list); } else { @@ -348,9 +354,11 @@ int using_ftrace_ops_list_func(void) return ftrace_trace_function == ftrace_ops_list_func; } -static void add_ftrace_ops(struct ftrace_ops **list, struct ftrace_ops *ops) +static void add_ftrace_ops(struct ftrace_ops __rcu **list, + struct ftrace_ops *ops) { - ops->next = *list; + rcu_assign_pointer(ops->next, *list); + /* * We are entering ops into the list but another * CPU might be walking that list. We need to make sure @@ -360,7 +368,8 @@ static void add_ftrace_ops(struct ftrace_ops **list, struct ftrace_ops *ops) rcu_assign_pointer(*list, ops); } -static int remove_ftrace_ops(struct ftrace_ops **list, struct ftrace_ops *ops) +static int remove_ftrace_ops(struct ftrace_ops __rcu **list, + struct ftrace_ops *ops) { struct ftrace_ops **p; @@ -368,7 +377,10 @@ static int remove_ftrace_ops(struct ftrace_ops **list, struct ftrace_ops *ops) * If we are removing the last function, then simply point * to the ftrace_stub. */ - if (*list == ops && ops->next == &ftrace_list_end) { + if (rcu_dereference_protected(*list, + lockdep_is_held(&ftrace_lock)) == ops && + rcu_dereference_protected(ops->next, + lockdep_is_held(&ftrace_lock)) == &ftrace_list_end) { *list = &ftrace_list_end; return 0; } @@ -1513,8 +1525,8 @@ ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip, void *regs) return 0; #endif - hash.filter_hash = rcu_dereference_raw_notrace(ops->func_hash->filter_hash); - hash.notrace_hash = rcu_dereference_raw_notrace(ops->func_hash->notrace_hash); + rcu_assign_pointer(hash.filter_hash, ops->func_hash->filter_hash); + rcu_assign_pointer(hash.notrace_hash, ops->func_hash->notrace_hash); if (hash_contains_ip(ip, &hash)) ret = 1; @@ -2784,7 +2796,8 @@ static int ftrace_shutdown(struct ftrace_ops *ops, int command) * If there's no more ops registered with ftrace, run a * sanity check to make sure all rec flags are cleared. */ - if (ftrace_ops_list == &ftrace_list_end) { + if (rcu_dereference_protected(ftrace_ops_list, + lockdep_is_held(&ftrace_lock)) == &ftrace_list_end) { struct ftrace_page *pg; struct dyn_ftrace *rec; @@ -6122,7 +6135,8 @@ ftrace_enable_sysctl(struct ctl_table *table, int write, if (ftrace_enabled) { /* we are starting ftrace again */ - if (ftrace_ops_list != &ftrace_list_end) + if (rcu_dereference_protected(ftrace_ops_list, + lockdep_is_held(&ftrace_lock)) != &ftrace_list_end) update_ftrace_function(); ftrace_startup_sysctl(); diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 291a1bc..60b26b4 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -1183,9 +1183,9 @@ struct ftrace_event_field { struct event_filter { int n_preds; /* Number assigned */ int a_preds; /* allocated */ - struct filter_pred *preds; - struct filter_pred *root; - char *filter_string; + struct filter_pred __rcu *preds; + struct filter_pred __rcu *root; + char *filter_string; }; struct event_subsystem {