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-rw-r--r--kernel/trace/trace.h64
1 files changed, 20 insertions, 44 deletions
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 7150892c692a..d8032be31405 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -431,23 +431,8 @@ struct tracer {
* When function tracing occurs, the following steps are made:
* If arch does not support a ftrace feature:
* call internal function (uses INTERNAL bits) which calls...
- * If callback is registered to the "global" list, the list
- * function is called and recursion checks the GLOBAL bits.
- * then this function calls...
* The function callback, which can use the FTRACE bits to
* check for recursion.
- *
- * Now if the arch does not suppport a feature, and it calls
- * the global list function which calls the ftrace callback
- * all three of these steps will do a recursion protection.
- * There's no reason to do one if the previous caller already
- * did. The recursion that we are protecting against will
- * go through the same steps again.
- *
- * To prevent the multiple recursion checks, if a recursion
- * bit is set that is higher than the MAX bit of the current
- * check, then we know that the check was made by the previous
- * caller, and we can skip the current check.
*/
enum {
TRACE_BUFFER_BIT,
@@ -460,12 +445,14 @@ enum {
TRACE_FTRACE_NMI_BIT,
TRACE_FTRACE_IRQ_BIT,
TRACE_FTRACE_SIRQ_BIT,
+ TRACE_FTRACE_TRANSITION_BIT,
- /* INTERNAL_BITs must be greater than FTRACE_BITs */
+ /* Internal use recursion bits */
TRACE_INTERNAL_BIT,
TRACE_INTERNAL_NMI_BIT,
TRACE_INTERNAL_IRQ_BIT,
TRACE_INTERNAL_SIRQ_BIT,
+ TRACE_INTERNAL_TRANSITION_BIT,
TRACE_CONTROL_BIT,
@@ -478,12 +465,6 @@ enum {
* can only be modified by current, we can reuse trace_recursion.
*/
TRACE_IRQ_BIT,
-
- /*
- * When transitioning between context, the preempt_count() may
- * not be correct. Allow for a single recursion to cover this case.
- */
- TRACE_TRANSITION_BIT,
};
#define trace_recursion_set(bit) do { (current)->trace_recursion |= (1<<(bit)); } while (0)
@@ -493,12 +474,18 @@ enum {
#define TRACE_CONTEXT_BITS 4
#define TRACE_FTRACE_START TRACE_FTRACE_BIT
-#define TRACE_FTRACE_MAX ((1 << (TRACE_FTRACE_START + TRACE_CONTEXT_BITS)) - 1)
#define TRACE_LIST_START TRACE_INTERNAL_BIT
-#define TRACE_LIST_MAX ((1 << (TRACE_LIST_START + TRACE_CONTEXT_BITS)) - 1)
-#define TRACE_CONTEXT_MASK TRACE_LIST_MAX
+#define TRACE_CONTEXT_MASK ((1 << (TRACE_LIST_START + TRACE_CONTEXT_BITS)) - 1)
+
+enum {
+ TRACE_CTX_NMI,
+ TRACE_CTX_IRQ,
+ TRACE_CTX_SOFTIRQ,
+ TRACE_CTX_NORMAL,
+ TRACE_CTX_TRANSITION,
+};
static __always_inline int trace_get_context_bit(void)
{
@@ -506,59 +493,48 @@ static __always_inline int trace_get_context_bit(void)
if (in_interrupt()) {
if (in_nmi())
- bit = 0;
+ bit = TRACE_CTX_NMI;
else if (in_irq())
- bit = 1;
+ bit = TRACE_CTX_IRQ;
else
- bit = 2;
+ bit = TRACE_CTX_SOFTIRQ;
} else
- bit = 3;
+ bit = TRACE_CTX_NORMAL;
return bit;
}
-static __always_inline int trace_test_and_set_recursion(int start, int max)
+static __always_inline int trace_test_and_set_recursion(int start)
{
unsigned int val = current->trace_recursion;
int bit;
- /* A previous recursion check was made */
- if ((val & TRACE_CONTEXT_MASK) > max)
- return 0;
-
bit = trace_get_context_bit() + start;
if (unlikely(val & (1 << bit))) {
/*
* It could be that preempt_count has not been updated during
* a switch between contexts. Allow for a single recursion.
*/
- bit = TRACE_TRANSITION_BIT;
+ bit = start + TRACE_CTX_TRANSITION;
if (trace_recursion_test(bit))
return -1;
trace_recursion_set(bit);
barrier();
- return bit + 1;
+ return bit;
}
- /* Normal check passed, clear the transition to allow it again */
- trace_recursion_clear(TRACE_TRANSITION_BIT);
-
val |= 1 << bit;
current->trace_recursion = val;
barrier();
- return bit + 1;
+ return bit;
}
static __always_inline void trace_clear_recursion(int bit)
{
unsigned int val = current->trace_recursion;
- if (!bit)
- return;
-
- bit--;
bit = 1 << bit;
val &= ~bit;