coresight: Fix signedness bug in tmc_etr_buf_insert_barrier_packet()

stable inclusion
from stable-v5.10.181
commit b663696c06527c9649d66f5176a3098554cef0d6
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8GJZJ

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b663696c06527c9649d66f5176a3098554cef0d6



--------------------------------

commit f67bc15e upstream.

This code generates a Smatch warning:

    drivers/hwtracing/coresight/coresight-tmc-etr.c:947 tmc_etr_buf_insert_barrier_packet()
    error: uninitialized symbol 'bufp'.

The problem is that if tmc_sg_table_get_data() returns -EINVAL, then
when we test if "len < CORESIGHT_BARRIER_PKT_SIZE", the negative "len"
value is type promoted to a high unsigned long value which is greater
than CORESIGHT_BARRIER_PKT_SIZE.  Fix this bug by adding an explicit
check for error codes.

Fixes: 75f4e361 ("coresight: tmc-etr: Add transparent buffer management")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/7d33e244-d8b9-4c27-9653-883a13534b01@kili.mountain


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>
(cherry picked from commit 81db8567)