From c29f122cd7fc178b72b1335b1fce0dff2e5c0f5d Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Fri, 2 Nov 2012 17:17:59 -0400 Subject: [PATCH] ftrace: Add context level recursion bit checking Currently for recursion checking in the function tracer, ftrace tests a task_struct bit to determine if the function tracer had recursed or not. If it has, then it will will return without going further. But this leads to races. If an interrupt came in after the bit was set, the functions being traced would see that bit set and think that the function tracer recursed on itself, and would return. Instead add a bit for each context (normal, softirq, irq and nmi). A check of which context the task is in is made before testing the associated bit. Now if an interrupt preempts the function tracer after the previous context has been set, the interrupt functions can still be traced. Signed-off-by: Steven Rostedt --- kernel/trace/ftrace.c | 40 +++++++++++++++++++++++++++++++++------- kernel/trace/trace.h | 12 +++++++++--- 2 files changed, 42 insertions(+), 10 deletions(-) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 1330969d8447..639b6ab1f04c 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -156,14 +156,27 @@ static void ftrace_global_list_func(unsigned long ip, unsigned long parent_ip, struct ftrace_ops *op, struct pt_regs *regs) { - if (unlikely(trace_recursion_test(TRACE_GLOBAL_BIT))) + int bit; + + if (in_interrupt()) { + if (in_nmi()) + bit = TRACE_GLOBAL_NMI_BIT; + + else if (in_irq()) + bit = TRACE_GLOBAL_IRQ_BIT; + else + bit = TRACE_GLOBAL_SIRQ_BIT; + } else + bit = TRACE_GLOBAL_BIT; + + if (unlikely(trace_recursion_test(bit))) return; - trace_recursion_set(TRACE_GLOBAL_BIT); + trace_recursion_set(bit); do_for_each_ftrace_op(op, ftrace_global_list) { op->func(ip, parent_ip, op, regs); } while_for_each_ftrace_op(op); - trace_recursion_clear(TRACE_GLOBAL_BIT); + trace_recursion_clear(bit); } static void ftrace_pid_func(unsigned long ip, unsigned long parent_ip, @@ -4132,14 +4145,27 @@ __ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip, struct ftrace_ops *ignored, struct pt_regs *regs) { struct ftrace_ops *op; + unsigned int bit; if (function_trace_stop) return; - if (unlikely(trace_recursion_test(TRACE_INTERNAL_BIT))) - return; + if (in_interrupt()) { + if (in_nmi()) + bit = TRACE_INTERNAL_NMI_BIT; + + else if (in_irq()) + bit = TRACE_INTERNAL_IRQ_BIT; + else + bit = TRACE_INTERNAL_SIRQ_BIT; + } else + bit = TRACE_INTERNAL_BIT; + + if (unlikely(trace_recursion_test(bit))) + return; + + trace_recursion_set(bit); - trace_recursion_set(TRACE_INTERNAL_BIT); /* * Some of the ops may be dynamically allocated, * they must be freed after a synchronize_sched(). @@ -4150,7 +4176,7 @@ __ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip, op->func(ip, parent_ip, op, regs); } while_for_each_ftrace_op(op); preempt_enable_notrace(); - trace_recursion_clear(TRACE_INTERNAL_BIT); + trace_recursion_clear(bit); } /* diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index c75d7988902c..fe6ccff9cc70 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -299,8 +299,14 @@ struct tracer { /* for function tracing recursion */ #define TRACE_INTERNAL_BIT (1<<11) -#define TRACE_GLOBAL_BIT (1<<12) -#define TRACE_CONTROL_BIT (1<<13) +#define TRACE_INTERNAL_NMI_BIT (1<<12) +#define TRACE_INTERNAL_IRQ_BIT (1<<13) +#define TRACE_INTERNAL_SIRQ_BIT (1<<14) +#define TRACE_GLOBAL_BIT (1<<15) +#define TRACE_GLOBAL_NMI_BIT (1<<16) +#define TRACE_GLOBAL_IRQ_BIT (1<<17) +#define TRACE_GLOBAL_SIRQ_BIT (1<<18) +#define TRACE_CONTROL_BIT (1<<19) /* * Abuse of the trace_recursion. @@ -309,7 +315,7 @@ struct tracer { * was called in irq context but we have irq tracing off. Since this * can only be modified by current, we can reuse trace_recursion. */ -#define TRACE_IRQ_BIT (1<<13) +#define TRACE_IRQ_BIT (1<<20) #define trace_recursion_set(bit) do { (current)->trace_recursion |= (bit); } while (0) #define trace_recursion_clear(bit) do { (current)->trace_recursion &= ~(bit); } while (0) -- 2.20.1