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Diffstat (limited to 'include/linux/trace_recursion.h')
-rw-r--r--include/linux/trace_recursion.h49
1 files changed, 9 insertions, 40 deletions
diff --git a/include/linux/trace_recursion.h b/include/linux/trace_recursion.h
index a9f9c5714e65..fe95f0922526 100644
--- a/include/linux/trace_recursion.h
+++ b/include/linux/trace_recursion.h
@@ -16,23 +16,8 @@
* 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 support 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 {
/* Function recursion bits */
@@ -40,12 +25,14 @@ 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_BRANCH_BIT,
/*
@@ -86,12 +73,6 @@ enum {
*/
TRACE_GRAPH_NOTRACE_BIT,
- /*
- * When transitioning between context, the preempt_count() may
- * not be correct. Allow for a single recursion to cover this case.
- */
- TRACE_TRANSITION_BIT,
-
/* Used to prevent recursion recording from recursing. */
TRACE_RECORD_RECURSION_BIT,
};
@@ -113,12 +94,10 @@ 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)
/*
* Used for setting context
@@ -132,6 +111,7 @@ enum {
TRACE_CTX_IRQ,
TRACE_CTX_SOFTIRQ,
TRACE_CTX_NORMAL,
+ TRACE_CTX_TRANSITION,
};
static __always_inline int trace_get_context_bit(void)
@@ -160,45 +140,34 @@ extern void ftrace_record_recursion(unsigned long ip, unsigned long parent_ip);
#endif
static __always_inline int trace_test_and_set_recursion(unsigned long ip, unsigned long pip,
- int start, int max)
+ int start)
{
unsigned int val = READ_ONCE(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 = TRACE_CTX_TRANSITION + start;
if (val & (1 << bit)) {
do_ftrace_record_recursion(ip, pip);
return -1;
}
- } else {
- /* Normal check passed, clear the transition to allow it again */
- val &= ~(1 << 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)
{
- if (!bit)
- return;
-
barrier();
- bit--;
trace_recursion_clear(bit);
}
@@ -214,7 +183,7 @@ static __always_inline void trace_clear_recursion(int bit)
static __always_inline int ftrace_test_recursion_trylock(unsigned long ip,
unsigned long parent_ip)
{
- return trace_test_and_set_recursion(ip, parent_ip, TRACE_FTRACE_START, TRACE_FTRACE_MAX);
+ return trace_test_and_set_recursion(ip, parent_ip, TRACE_FTRACE_START);
}
/**