From cbb042fd8794b7db5f8bfb978c761b6b9fb4c4f5 Mon Sep 17 00:00:00 2001 From: Tom Zanussi Date: Tue, 18 Dec 2018 14:33:23 -0600 Subject: [PATCH] tracing: Remove open-coding of hist trigger var_ref management commit de40f033d4e84e843d6a12266e3869015ea9097c upstream. Have create_var_ref() manage the hist trigger's var_ref list, rather than having similar code doing it in multiple places. This cleans up the code and makes sure var_refs are always accounted properly. Also, document the var_ref-related functions to make what their purpose clearer. Link: http://lkml.kernel.org/r/05ddae93ff514e66fc03897d6665231892939913.1545161087.git.tom.zanussi@linux.intel.com Acked-by: Namhyung Kim Reviewed-by: Masami Hiramatsu Signed-off-by: Tom Zanussi Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Greg Kroah-Hartman --- kernel/trace/trace_events_hist.c | 93 ++++++++++++++++++++++++++++++++-------- 1 file changed, 75 insertions(+), 18 deletions(-) diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index d606c0e5..4beac53 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -1274,6 +1274,17 @@ static u64 hist_field_cpu(struct hist_field *hist_field, return cpu; } +/** + * check_field_for_var_ref - Check if a VAR_REF field references a variable + * @hist_field: The VAR_REF field to check + * @var_data: The hist trigger that owns the variable + * @var_idx: The trigger variable identifier + * + * Check the given VAR_REF field to see whether or not it references + * the given variable associated with the given trigger. + * + * Return: The VAR_REF field if it does reference the variable, NULL if not + */ static struct hist_field * check_field_for_var_ref(struct hist_field *hist_field, struct hist_trigger_data *var_data, @@ -1324,6 +1335,18 @@ check_field_for_var_refs(struct hist_trigger_data *hist_data, return found; } +/** + * find_var_ref - Check if a trigger has a reference to a trigger variable + * @hist_data: The hist trigger that might have a reference to the variable + * @var_data: The hist trigger that owns the variable + * @var_idx: The trigger variable identifier + * + * Check the list of var_refs[] on the first hist trigger to see + * whether any of them are references to the variable on the second + * trigger. + * + * Return: The VAR_REF field referencing the variable if so, NULL if not + */ static struct hist_field *find_var_ref(struct hist_trigger_data *hist_data, struct hist_trigger_data *var_data, unsigned int var_idx) @@ -1350,6 +1373,20 @@ static struct hist_field *find_var_ref(struct hist_trigger_data *hist_data, return found; } +/** + * find_any_var_ref - Check if there is a reference to a given trigger variable + * @hist_data: The hist trigger + * @var_idx: The trigger variable identifier + * + * Check to see whether the given variable is currently referenced by + * any other trigger. + * + * The trigger the variable is defined on is explicitly excluded - the + * assumption being that a self-reference doesn't prevent a trigger + * from being removed. + * + * Return: The VAR_REF field referencing the variable if so, NULL if not + */ static struct hist_field *find_any_var_ref(struct hist_trigger_data *hist_data, unsigned int var_idx) { @@ -1368,6 +1405,19 @@ static struct hist_field *find_any_var_ref(struct hist_trigger_data *hist_data, return found; } +/** + * check_var_refs - Check if there is a reference to any of trigger's variables + * @hist_data: The hist trigger + * + * A trigger can define one or more variables. If any one of them is + * currently referenced by any other trigger, this function will + * determine that. + + * Typically used to determine whether or not a trigger can be removed + * - if there are any references to a trigger's variables, it cannot. + * + * Return: True if there is a reference to any of trigger's variables + */ static bool check_var_refs(struct hist_trigger_data *hist_data) { struct hist_field *field; @@ -2392,7 +2442,23 @@ static int init_var_ref(struct hist_field *ref_field, goto out; } -static struct hist_field *create_var_ref(struct hist_field *var_field, +/** + * create_var_ref - Create a variable reference and attach it to trigger + * @hist_data: The trigger that will be referencing the variable + * @var_field: The VAR field to create a reference to + * @system: The optional system string + * @event_name: The optional event_name string + * + * Given a variable hist_field, create a VAR_REF hist_field that + * represents a reference to it. + * + * This function also adds the reference to the trigger that + * now references the variable. + * + * Return: The VAR_REF field if successful, NULL if not + */ +static struct hist_field *create_var_ref(struct hist_trigger_data *hist_data, + struct hist_field *var_field, char *system, char *event_name) { unsigned long flags = HIST_FIELD_FL_VAR_REF; @@ -2404,6 +2470,9 @@ static struct hist_field *create_var_ref(struct hist_field *var_field, destroy_hist_field(ref_field, 0); return NULL; } + + hist_data->var_refs[hist_data->n_var_refs] = ref_field; + ref_field->var_ref_idx = hist_data->n_var_refs++; } return ref_field; @@ -2477,7 +2546,8 @@ static struct hist_field *parse_var_ref(struct hist_trigger_data *hist_data, var_field = find_event_var(hist_data, system, event_name, var_name); if (var_field) - ref_field = create_var_ref(var_field, system, event_name); + ref_field = create_var_ref(hist_data, var_field, + system, event_name); if (!ref_field) hist_err_event("Couldn't find variable: $", @@ -2597,8 +2667,6 @@ static struct hist_field *parse_atom(struct hist_trigger_data *hist_data, if (!s) { hist_field = parse_var_ref(hist_data, ref_system, ref_event, ref_var); if (hist_field) { - hist_data->var_refs[hist_data->n_var_refs] = hist_field; - hist_field->var_ref_idx = hist_data->n_var_refs++; if (var_name) { hist_field = create_alias(hist_data, hist_field, var_name); if (!hist_field) { @@ -3376,7 +3444,6 @@ static int onmax_create(struct hist_trigger_data *hist_data, unsigned int var_ref_idx = hist_data->n_var_refs; struct field_var *field_var; char *onmax_var_str, *param; - unsigned long flags; unsigned int i; int ret = 0; @@ -3393,18 +3460,10 @@ static int onmax_create(struct hist_trigger_data *hist_data, return -EINVAL; } - flags = HIST_FIELD_FL_VAR_REF; - ref_field = create_hist_field(hist_data, NULL, flags, NULL); + ref_field = create_var_ref(hist_data, var_field, NULL, NULL); if (!ref_field) return -ENOMEM; - if (init_var_ref(ref_field, var_field, NULL, NULL)) { - destroy_hist_field(ref_field, 0); - ret = -ENOMEM; - goto out; - } - hist_data->var_refs[hist_data->n_var_refs] = ref_field; - ref_field->var_ref_idx = hist_data->n_var_refs++; data->onmax.var = ref_field; data->fn = onmax_save; @@ -3595,9 +3654,6 @@ static void save_synth_var_ref(struct hist_trigger_data *hist_data, struct hist_field *var_ref) { hist_data->synth_var_refs[hist_data->n_synth_var_refs++] = var_ref; - - hist_data->var_refs[hist_data->n_var_refs] = var_ref; - var_ref->var_ref_idx = hist_data->n_var_refs++; } static int check_synth_field(struct synth_event *event, @@ -3752,7 +3808,8 @@ static int onmatch_create(struct hist_trigger_data *hist_data, } if (check_synth_field(event, hist_field, field_pos) == 0) { - var_ref = create_var_ref(hist_field, system, event_name); + var_ref = create_var_ref(hist_data, hist_field, + system, event_name); if (!var_ref) { kfree(p); ret = -ENOMEM; -- 2.7.4