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: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c
index 79cca94..0db303b 100644
--- a/drivers/hwtracing/stm/core.c
+++ b/drivers/hwtracing/stm/core.c
@@ -380,8 +380,8 @@
return ret;
}
-static void stm_write(struct stm_data *data, unsigned int master,
- unsigned int channel, const char *buf, size_t count)
+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;
const unsigned char *p = buf, nil = 0;
@@ -393,9 +393,14 @@
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 @@
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);
@@ -996,9 +1001,9 @@
stm = srcu_dereference(src->link, &stm_source_srcu);
if (stm)
- stm_write(stm->data, src->output.master,
- src->output.channel + chan,
- buf, count);
+ count = stm_write(stm->data, src->output.master,
+ src->output.channel + chan,
+ buf, count);
else
count = -ENODEV;