diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 8a4b49c99f22..acd366e4ab1a 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -1986,83 +1986,41 @@ static void __trace_userstack(struct trace_array *tr, unsigned long flags) /* created for use with alloc_percpu */ struct trace_buffer_struct { - char buffer[TRACE_BUF_SIZE]; + int nesting; + char buffer[4][TRACE_BUF_SIZE]; }; static struct trace_buffer_struct *trace_percpu_buffer; -static struct trace_buffer_struct *trace_percpu_sirq_buffer; -static struct trace_buffer_struct *trace_percpu_irq_buffer; -static struct trace_buffer_struct *trace_percpu_nmi_buffer; /* - * The buffer used is dependent on the context. There is a per cpu - * buffer for normal context, softirq contex, hard irq context and - * for NMI context. Thise allows for lockless recording. - * - * Note, if the buffers failed to be allocated, then this returns NULL + * Thise allows for lockless recording. If we're nested too deeply, then + * this returns NULL. */ static char *get_trace_buf(void) { - struct trace_buffer_struct *percpu_buffer; - - /* - * If we have allocated per cpu buffers, then we do not - * need to do any locking. - */ - if (in_nmi()) - percpu_buffer = trace_percpu_nmi_buffer; - else if (in_irq()) - percpu_buffer = trace_percpu_irq_buffer; - else if (in_softirq()) - percpu_buffer = trace_percpu_sirq_buffer; - else - percpu_buffer = trace_percpu_buffer; + struct trace_buffer_struct *buffer = this_cpu_ptr(trace_percpu_buffer); - if (!percpu_buffer) + if (!buffer || buffer->nesting >= 4) return NULL; - return this_cpu_ptr(&percpu_buffer->buffer[0]); + return &buffer->buffer[buffer->nesting++][0]; +} + +static void put_trace_buf(void) +{ + this_cpu_dec(trace_percpu_buffer->nesting); } static int alloc_percpu_trace_buffer(void) { struct trace_buffer_struct *buffers; - struct trace_buffer_struct *sirq_buffers; - struct trace_buffer_struct *irq_buffers; - struct trace_buffer_struct *nmi_buffers; buffers = alloc_percpu(struct trace_buffer_struct); - if (!buffers) - goto err_warn; - - sirq_buffers = alloc_percpu(struct trace_buffer_struct); - if (!sirq_buffers) - goto err_sirq; - - irq_buffers = alloc_percpu(struct trace_buffer_struct); - if (!irq_buffers) - goto err_irq; - - nmi_buffers = alloc_percpu(struct trace_buffer_struct); - if (!nmi_buffers) - goto err_nmi; + if (WARN(!buffers, "Could not allocate percpu trace_printk buffer")) + return -ENOMEM; trace_percpu_buffer = buffers; - trace_percpu_sirq_buffer = sirq_buffers; - trace_percpu_irq_buffer = irq_buffers; - trace_percpu_nmi_buffer = nmi_buffers; - return 0; - - err_nmi: - free_percpu(irq_buffers); - err_irq: - free_percpu(sirq_buffers); - err_sirq: - free_percpu(buffers); - err_warn: - WARN(1, "Could not allocate percpu trace_printk buffer"); - return -ENOMEM; } static int buffers_allocated; @@ -2153,7 +2111,7 @@ int trace_vbprintk(unsigned long ip, const char *fmt, va_list args) tbuffer = get_trace_buf(); if (!tbuffer) { len = 0; - goto out; + goto out_nobuffer; } len = vbin_printf((u32 *)tbuffer, TRACE_BUF_SIZE/sizeof(int), fmt, args); @@ -2179,6 +2137,9 @@ int trace_vbprintk(unsigned long ip, const char *fmt, va_list args) } out: + put_trace_buf(); + +out_nobuffer: preempt_enable_notrace(); unpause_graph_tracing(); @@ -2210,7 +2171,7 @@ __trace_array_vprintk(struct ring_buffer *buffer, tbuffer = get_trace_buf(); if (!tbuffer) { len = 0; - goto out; + goto out_nobuffer; } len = vscnprintf(tbuffer, TRACE_BUF_SIZE, fmt, args); @@ -2229,7 +2190,11 @@ __trace_array_vprintk(struct ring_buffer *buffer, __buffer_unlock_commit(buffer, event); ftrace_trace_stack(&global_trace, buffer, flags, 6, pc, NULL); } - out: + +out_nobuffer: + put_trace_buf(); + +out: preempt_enable_notrace(); unpause_graph_tracing();