tracing: kdb: Fix ftdump to not sleep

[mirror_ubuntu-bionic-kernel.git] / kernel / trace / ring_buffer.c

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 0cddf60186da0b72b0db7b57fd115030c0ee6126..69a09f0907ef232422b92670947329a22af0559f 100644 (file)
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1136,6 +1136,11 @@ static int __rb_allocate_pages(long nr_pages, struct list_head *pages, int cpu)
        struct buffer_page *bpage, *tmp;
        long i;
 
+       /* Check if the available memory is there first */
+       i = si_mem_available();
+       if (i < nr_pages)
+               return -ENOMEM;
+
        for (i = 0; i < nr_pages; i++) {
                struct page *page;
                /*
@@ -1474,6 +1479,8 @@ rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned long nr_pages)
        tmp_iter_page = first_page;
 
        do {
+               cond_resched();
+
                to_remove_page = tmp_iter_page;
                rb_inc_page(cpu_buffer, &tmp_iter_page);
 
@@ -2579,8 +2586,7 @@ trace_recursive_lock(struct ring_buffer_per_cpu *cpu_buffer)
                bit = RB_CTX_NORMAL;
        else
                bit = pc & NMI_MASK ? RB_CTX_NMI :
-                       pc & HARDIRQ_MASK ? RB_CTX_IRQ :
-                       pc & SOFTIRQ_OFFSET ? 2 : RB_CTX_SOFTIRQ;
+                       pc & HARDIRQ_MASK ? RB_CTX_IRQ : RB_CTX_SOFTIRQ;
 
        if (unlikely(val & (1 << bit)))
                return 1;
@@ -3096,6 +3102,22 @@ int ring_buffer_record_is_on(struct ring_buffer *buffer)
        return !atomic_read(&buffer->record_disabled);
 }
 
+/**
+ * ring_buffer_record_is_set_on - return true if the ring buffer is set writable
+ * @buffer: The ring buffer to see if write is set enabled
+ *
+ * Returns true if the ring buffer is set writable by ring_buffer_record_on().
+ * Note that this does NOT mean it is in a writable state.
+ *
+ * It may return true when the ring buffer has been disabled by
+ * ring_buffer_record_disable(), as that is a temporary disabling of
+ * the ring buffer.
+ */
+int ring_buffer_record_is_set_on(struct ring_buffer *buffer)
+{
+       return !(atomic_read(&buffer->record_disabled) & RB_BUFFER_OFF);
+}
+
 /**
  * ring_buffer_record_disable_cpu - stop all writes into the cpu_buffer
  * @buffer: The ring buffer to stop writes to.
@@ -3979,6 +4001,7 @@ EXPORT_SYMBOL_GPL(ring_buffer_consume);
  * ring_buffer_read_prepare - Prepare for a non consuming read of the buffer
  * @buffer: The ring buffer to read from
  * @cpu: The cpu buffer to iterate over
+ * @flags: gfp flags to use for memory allocation
  *
  * This performs the initial preparations necessary to iterate
  * through the buffer.  Memory is allocated, buffer recording
@@ -3996,7 +4019,7 @@ EXPORT_SYMBOL_GPL(ring_buffer_consume);
  * This overall must be paired with ring_buffer_read_finish.
  */
 struct ring_buffer_iter *
-ring_buffer_read_prepare(struct ring_buffer *buffer, int cpu)
+ring_buffer_read_prepare(struct ring_buffer *buffer, int cpu, gfp_t flags)
 {
        struct ring_buffer_per_cpu *cpu_buffer;
        struct ring_buffer_iter *iter;
@@ -4004,7 +4027,7 @@ ring_buffer_read_prepare(struct ring_buffer *buffer, int cpu)
        if (!cpumask_test_cpu(cpu, buffer->cpumask))
                return NULL;
 
-       iter = kmalloc(sizeof(*iter), GFP_KERNEL);
+       iter = kmalloc(sizeof(*iter), flags);
        if (!iter)
                return NULL;