Commit f8560a9b authored by Alexander Shishkin's avatar Alexander Shishkin Committed by Greg Kroah-Hartman
Browse files

stm class: Use driver's packet callback return value 



STM drivers provide a callback to generate/send individual STP packets;
it also tells the stm core how many bytes of payload it has consumed.
However, we would also need to use the negative space of this return
value to communicate errors that occur during the packet generation,
in which case the stm core will have to take appropriate action.

For now, we need to account for the possibility that the stm driver may
not support certain combinations of packet type/flags, in which case
it is expected to signal an error.

Signed-off-by: default avatarAlexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 14136e36

drivers/hwtracing/stm/core.c

+12 −7
Original line number Diff line number Diff line
@@ -380,7 +380,7 @@ static int stm_file_assign(struct stm_file *stmf, char *id, unsigned int width) 
	return ret;

}



static void stm_write(struct stm_data *data, unsigned int master,

static ssize_t stm_write(struct stm_data *data, unsigned int master,

			  unsigned int channel, const char *buf, size_t count)

{

	unsigned int flags = STP_PACKET_TIMESTAMPED;
@@ -393,9 +393,14 @@ static void stm_write(struct stm_data *data, unsigned int master, 
		sz = data->packet(data, master, channel, STP_PACKET_DATA, flags,

				  sz, p);

		flags = 0;



		if (sz < 0)

			break;

	}



	data->packet(data, master, channel, STP_PACKET_FLAG, 0, 0, &nil);



	return pos;

}



static ssize_t stm_char_write(struct file *file, const char __user *buf,
@@ -433,8 +438,8 @@ static ssize_t stm_char_write(struct file *file, const char __user *buf, 
		return -EFAULT;

	}



	stm_write(stm->data, stmf->output.master, stmf->output.channel, kbuf,

		  count);

	count = stm_write(stm->data, stmf->output.master, stmf->output.channel,

			  kbuf, count);



	kfree(kbuf);
@@ -996,7 +1001,7 @@ int stm_source_write(struct stm_source_data *data, unsigned int chan, 


	stm = srcu_dereference(src->link, &stm_source_srcu);

	if (stm)

		stm_write(stm->data, src->output.master,

		count = stm_write(stm->data, src->output.master,

				  src->output.channel + chan,

				  buf, count);

	else

include/linux/stm.h

+7 −0
Original line number Diff line number Diff line
@@ -67,6 +67,13 @@ struct stm_device; 
 * description. That is, the lowest master that can be allocated to software

 * writers is @sw_start and data from this writer will appear is @sw_start

 * master in the STP stream.

 *

 * The @packet callback should adhere to the following rules:

 *   1) it must return the number of bytes it consumed from the payload;

 *   2) therefore, if it sent a packet that does not have payload (like FLAG),

 *      it must return zero;

 *   3) if it does not support the requested packet type/flag combination,

 *      it must return -ENOTSUPP.

 */

struct stm_data {

	const char		*name;

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