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Commit f3e99f1a authored by Eric Holmberg's avatar Eric Holmberg
Browse files

trace: ipc_logging: fix non-destructive read logic 



When dumping logs through debugfs, a non-destructive read is performed
and after all data has been printed, the call waits on a completion for
new log data.  When that event is completed, the entire contents of the
logs are incorrectly printed.

Fix the read logic to correctly update the non-destructive read pointer
such that only the new data is printed to the logs.

CRs-Fixed: 681317
Change-Id: Ia12787b576b18b9f5174cefe91eb283979c286f7
Signed-off-by: default avatarEric Holmberg <eholmber@codeaurora.org>
parent 9a9c1f23

kernel/trace/ipc_logging.c

+33 −13
Original line number Diff line number Diff line
@@ -89,6 +89,30 @@ static int is_read_empty(struct ipc_log_context *ilctxt) 
		 ilctxt->write_page->hdr.write_offset));

}



/**

 * is_nd_read_equal_read - Return true if the non-destructive read is equal to

 * the destructive read

 *

 * @ilctxt: logging context

 * @returns: true if nd read is equal to read; false otherwise

 */

static bool is_nd_read_equal_read(struct ipc_log_context *ilctxt)

{

	uint16_t read_offset;

	uint16_t nd_read_offset;



	if (ilctxt->nd_read_page == ilctxt->read_page) {

		read_offset = ilctxt->read_page->hdr.read_offset;

		nd_read_offset = ilctxt->nd_read_page->hdr.nd_read_offset;



		if (read_offset == nd_read_offset)

			return true;

	}



	return false;

}





static struct ipc_log_page *get_next_page(struct ipc_log_context *ilctxt,

					  struct ipc_log_page *cur_pg)

{
@@ -158,6 +182,7 @@ static void ipc_log_drop(struct ipc_log_context *ilctxt, void *data, 
		int data_size)

{

	int bytes_to_read;

	bool push_nd_read;



	bytes_to_read = MIN(LOG_PAGE_DATA_SIZE

				- ilctxt->read_page->hdr.read_offset,
@@ -168,10 +193,10 @@ static void ipc_log_drop(struct ipc_log_context *ilctxt, void *data, 


	if (bytes_to_read != data_size) {

		/* not enough space, wrap read to next page */

		ilctxt->read_page->hdr.read_offset = 0;

		push_nd_read = is_nd_read_equal_read(ilctxt);



		if (ilctxt->nd_read_page == ilctxt->read_page) {

			/* app reading from the same page */

		ilctxt->read_page->hdr.read_offset = 0;

		if (push_nd_read) {

			ilctxt->read_page->hdr.nd_read_offset = 0;

			ilctxt->read_page = get_next_page(ilctxt,

				ilctxt->read_page);
@@ -189,19 +214,14 @@ static void ipc_log_drop(struct ipc_log_context *ilctxt, void *data, 


		bytes_to_read = (data_size - bytes_to_read);

	}

	ilctxt->read_page->hdr.read_offset += bytes_to_read;

	ilctxt->write_avail += data_size;



	/* update non-destructive read pointer if necessary */

	if (ilctxt->nd_read_page == ilctxt->read_page) {

		uint16_t read_offset, nd_read_offset;



		read_offset = ilctxt->read_page->hdr.read_offset;

		nd_read_offset = ilctxt->nd_read_page->hdr.nd_read_offset;

	push_nd_read = is_nd_read_equal_read(ilctxt);

	ilctxt->read_page->hdr.read_offset += bytes_to_read;

	ilctxt->write_avail += data_size;



		if (read_offset > nd_read_offset)

			ilctxt->nd_read_page->hdr.nd_read_offset = read_offset;

	}

	if (push_nd_read)

		ilctxt->nd_read_page->hdr.nd_read_offset += bytes_to_read;

}



/**