Merge branch 'rework/fast-next-seq' into for-linus (5eb17c1f) · Commits · EulixOS / Software / Kernel

kernel/printk/printk_ringbuffer.c

+47 −5

Original line number	Diff line number	Diff line
		@@ -474,8 +474,10 @@ static enum desc_state desc_read(struct prb_desc_ring *desc_ring,
		* state has been re-checked. A memcpy() for all of @desc
		* cannot be used because of the atomic_t @state_var field.
		*/
		if (desc_out) {
		memcpy(&desc_out->text_blk_lpos, &desc->text_blk_lpos,
		sizeof(desc_out->text_blk_lpos)); /* LMM(desc_read:C) */
		}
		if (seq_out)
		seq_out = info->seq; / also part of desc_read:C */
		if (caller_id_out)
		@@ -528,6 +530,7 @@ static enum desc_state desc_read(struct prb_desc_ring *desc_ring,
		state_val = atomic_long_read(state_var); /* LMM(desc_read:E) */
		d_state = get_desc_state(id, state_val);
		out:
		if (desc_out)
		atomic_long_set(&desc_out->state_var, state_val);
		return d_state;
		}
		@@ -1449,6 +1452,9 @@ static void desc_make_final(struct prb_desc_ring *desc_ring, unsigned long id)

		atomic_long_cmpxchg_relaxed(&d->state_var, prev_state_val,
		DESC_SV(id, desc_finalized)); /* LMM(desc_make_final:A) */

		/* Best effort to remember the last finalized @id. */
		atomic_long_set(&desc_ring->last_finalized_id, id);
		}

		/**
		@@ -1657,7 +1663,12 @@ void prb_commit(struct prb_reserved_entry *e)
		*/
		void prb_final_commit(struct prb_reserved_entry *e)
		{
		struct prb_desc_ring *desc_ring = &e->rb->desc_ring;

		_prb_commit(e, desc_finalized);

		/* Best effort to remember the last finalized @id. */
		atomic_long_set(&desc_ring->last_finalized_id, e->id);
		}

		/*
		@@ -2005,9 +2016,39 @@ u64 prb_first_valid_seq(struct printk_ringbuffer *rb)
		*/
		u64 prb_next_seq(struct printk_ringbuffer *rb)
		{
		u64 seq = 0;
		struct prb_desc_ring *desc_ring = &rb->desc_ring;
		enum desc_state d_state;
		unsigned long id;
		u64 seq;

		/* Check if the cached @id still points to a valid @seq. */
		id = atomic_long_read(&desc_ring->last_finalized_id);
		d_state = desc_read(desc_ring, id, NULL, &seq, NULL);

		/* Search forward from the oldest descriptor. */
		if (d_state == desc_finalized \|\| d_state == desc_reusable) {
		/*
		* Begin searching after the last finalized record.
		*
		* On 0, the search must begin at 0 because of hack#2
		* of the bootstrapping phase it is not known if a
		* record at index 0 exists.
		*/
		if (seq != 0)
		seq++;
		} else {
		/*
		* The information about the last finalized sequence number
		* has gone. It should happen only when there is a flood of
		* new messages and the ringbuffer is rapidly recycled.
		* Give up and start from the beginning.
		*/
		seq = 0;
		}

		/*
		* The information about the last finalized @seq might be inaccurate.
		* Search forward to find the current one.
		*/
		while (_prb_read_valid(rb, &seq, NULL, NULL))
		seq++;

		@@ -2044,6 +2085,7 @@ void prb_init(struct printk_ringbuffer *rb,
		rb->desc_ring.infos = infos;
		atomic_long_set(&rb->desc_ring.head_id, DESC0_ID(descbits));
		atomic_long_set(&rb->desc_ring.tail_id, DESC0_ID(descbits));
		atomic_long_set(&rb->desc_ring.last_finalized_id, DESC0_ID(descbits));

		rb->text_data_ring.size_bits = textbits;
		rb->text_data_ring.data = text_buf;

kernel/printk/printk_ringbuffer.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -75,6 +75,7 @@ struct prb_desc_ring {
		struct printk_info *infos;
		atomic_long_t head_id;
		atomic_long_t tail_id;
		atomic_long_t last_finalized_id;
		};

		/*
		@@ -258,6 +259,7 @@ static struct printk_ringbuffer name = { \
		.infos = &_##name##_infos[0], \
		.head_id = ATOMIC_INIT(DESC0_ID(descbits)), \
		.tail_id = ATOMIC_INIT(DESC0_ID(descbits)), \
		.last_finalized_id = ATOMIC_INIT(DESC0_ID(descbits)), \
		}, \
		.text_data_ring = { \
		.size_bits = (avgtextbits) + (descbits), \