.../ABI/testing/configfs-stp-policy-p_ost | 6 + Documentation/trace/p_ost.rst | 36 +++ drivers/hwtracing/stm/Kconfig | 14 + drivers/hwtracing/stm/Makefile | 2 + drivers/hwtracing/stm/p_ost.c | 239 ++++++++++++++++++ 5 files changed, 297 insertions(+) create mode 100644 Documentation/ABI/testing/configfs-stp-policy-p_ost create mode 100644 Documentation/trace/p_ost.rst create mode 100644 drivers/hwtracing/stm/p_ost.c
Add MIPI OST(Open System Trace) protocol support for stm to format the
traces. The OST Protocol abstracts the underlying layers from the sending
and receiving applications, thus removing dependencies on the connection
media and platform implementation.
OST over STP packet consists of Header/Payload/End. Header is designed to
include the information required by all OST packets. Information that is
not shared by all packets is left to the higher layer protocols. Thus, the
OST Protocol Header can be regarded as the first part of a complete OST
Packet Header, while a higher layer header can be regarded as an extension
designed for a specific purpose.
+--------+--------+--------+--------+
| start |version |entity |protocol|
+--------+--------+--------+--------+
| stm version | magic |
+-----------------------------------+
| cpu |
+-----------------------------------+
| timestamp |
| |
+-----------------------------------+
| tgid |
| |
+-----------------------------------+
| payload |
+-----------------------------------+
| ... | end |
+-----------------------------------+
In header, there will be STARTSIMPLE/VERSION/ENTITY/PROTOCOL.
STARTSIMPLE is used to signal the beginning of a simplified OST protocol.
The Version field is a one byte, unsigned number identifying the version
of the OST Protocol. The Entity ID field is a one byte unsigned number
that identifies the source.
The Protocol ID field is a one byte unsigned number identifying the higher
layer protocol of the OST Packet, i.e. identifying the format of the data
after the OST Protocol Header. OST Control Protocol ID value represents
the common control protocol, the remaining Protocol ID values may be used
by any higher layer protocols capable of being transported by the OST
Protocol.
Signed-off-by: Tingwei Zhang <tingwei.zhang@oss.qualcomm.com>
Signed-off-by: Yuanfang Zhang <yuanfang.zhang@oss.qualcomm.com>
Signed-off-by: Jinlong Mao <jinlong.mao@oss.qualcomm.com>
Signed-off-by: Yingchao Deng <yingchao.deng@oss.qualcomm.com>
---
.../ABI/testing/configfs-stp-policy-p_ost | 6 +
Documentation/trace/p_ost.rst | 36 +++
drivers/hwtracing/stm/Kconfig | 14 +
drivers/hwtracing/stm/Makefile | 2 +
drivers/hwtracing/stm/p_ost.c | 239 ++++++++++++++++++
5 files changed, 297 insertions(+)
create mode 100644 Documentation/ABI/testing/configfs-stp-policy-p_ost
create mode 100644 Documentation/trace/p_ost.rst
create mode 100644 drivers/hwtracing/stm/p_ost.c
diff --git a/Documentation/ABI/testing/configfs-stp-policy-p_ost b/Documentation/ABI/testing/configfs-stp-policy-p_ost
new file mode 100644
index 000000000000..498739b49da0
--- /dev/null
+++ b/Documentation/ABI/testing/configfs-stp-policy-p_ost
@@ -0,0 +1,6 @@
+What: /config/stp-policy/<device>:p_ost.<policy>/<node>/entity
+Date: Oct 2025
+KernelVersion: 6.18
+Description:
+ Set the entity which is to identify the source, RW.
+
diff --git a/Documentation/trace/p_ost.rst b/Documentation/trace/p_ost.rst
new file mode 100644
index 000000000000..df93b889eb4c
--- /dev/null
+++ b/Documentation/trace/p_ost.rst
@@ -0,0 +1,36 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+===================
+MIPI OST over STP
+===================
+
+The OST(Open System Trace) driver is used with STM class devices to
+generate standardized trace stream. Trace sources can be identified
+by different entity ids.
+
+CONFIG_STM_PROTO_OST is for p_ost driver enablement. Once this config
+is enabled, you can select the p_ost protocol by command below:
+
+# mkdir /sys/kernel/config/stp-policy/stm0:p_ost.policy
+
+The policy name format is extended like this:
+ <device_name>:<protocol_name>.<policy_name>
+
+With coresight-stm device, it will be look like "stm0:p_ost.policy".
+
+With MIPI OST protocol driver, the attributes for each protocol node is:
+# mkdir /sys/kernel/config/stp-policy/stm0:p_ost.policy/default
+# ls /sys/kernel/config/stp-policy/stm0:p_ost.policy/default
+channels entity masters
+
+The entity here is the set the entity that p_ost supports. Currently
+p_ost supports ftrace, console and diag entity.
+
+Set entity:
+# echo 'ftrace' > /sys/kernel/config/stp-policy/stm0:p_ost.policy/default/entity
+
+Get available and currently selected (shown in square brackets) entity that p_ost supports:
+# cat /sys/kernel/config/stp-policy/stm0:p_ost.policy/default/entity
+[ftrace] console diag
+
+See Documentation/ABI/testing/configfs-stp-policy-p_ost for more details.
diff --git a/drivers/hwtracing/stm/Kconfig b/drivers/hwtracing/stm/Kconfig
index eda6b11d40a1..daa4aa09f64d 100644
--- a/drivers/hwtracing/stm/Kconfig
+++ b/drivers/hwtracing/stm/Kconfig
@@ -40,6 +40,20 @@ config STM_PROTO_SYS_T
If you don't know what this is, say N.
+config STM_PROTO_OST
+ tristate "MIPI OST STM framing protocol driver"
+ default CONFIG_STM
+ help
+ This is an implementation of MIPI OST protocol to be used
+ over the STP transport. In addition to the data payload, it
+ also carries additional metadata for entity, better
+ means of trace source identification, etc.
+
+ The receiving side must be able to decode this protocol in
+ addition to the MIPI STP, in order to extract the data.
+
+ If you don't know what this is, say N.
+
config STM_DUMMY
tristate "Dummy STM driver"
help
diff --git a/drivers/hwtracing/stm/Makefile b/drivers/hwtracing/stm/Makefile
index 1692fcd29277..d9c8615849b9 100644
--- a/drivers/hwtracing/stm/Makefile
+++ b/drivers/hwtracing/stm/Makefile
@@ -5,9 +5,11 @@ stm_core-y := core.o policy.o
obj-$(CONFIG_STM_PROTO_BASIC) += stm_p_basic.o
obj-$(CONFIG_STM_PROTO_SYS_T) += stm_p_sys-t.o
+obj-$(CONFIG_STM_PROTO_OST) += stm_p_ost.o
stm_p_basic-y := p_basic.o
stm_p_sys-t-y := p_sys-t.o
+stm_p_ost-y := p_ost.o
obj-$(CONFIG_STM_DUMMY) += dummy_stm.o
diff --git a/drivers/hwtracing/stm/p_ost.c b/drivers/hwtracing/stm/p_ost.c
new file mode 100644
index 000000000000..98bb62dfc5d3
--- /dev/null
+++ b/drivers/hwtracing/stm/p_ost.c
@@ -0,0 +1,239 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2025 Qualcomm Innovation Center, Inc. All rights reserved.
+ *
+ * MIPI OST framing protocol for STM devices.
+ */
+
+#include <linux/configfs.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/sched/clock.h>
+#include <linux/slab.h>
+#include <linux/stm.h>
+#include "stm.h"
+
+/*
+ * OST Base Protocol Header
+ *
+ * Position Bits Field Name
+ * 0 8 STARTSIMPLE
+ * 1 8 Version
+ * 2 8 Entity ID
+ * 3 8 protocol ID
+ */
+#define OST_FIELD_STARTSIMPLE 0
+#define OST_FIELD_VERSION 8
+#define OST_FIELD_ENTITY 16
+#define OST_FIELD_PROTOCOL 24
+
+#define OST_TOKEN_STARTSIMPLE 0x10
+#define OST_VERSION_MIPI1 0x10
+
+/* entity id to identify the source*/
+#define OST_ENTITY_FTRACE 0x01
+#define OST_ENTITY_CONSOLE 0x02
+#define OST_ENTITY_DIAG 0xEE
+
+#define OST_CONTROL_PROTOCOL 0x0
+
+#define DATA_HEADER ((OST_TOKEN_STARTSIMPLE << OST_FIELD_STARTSIMPLE) | \
+ (OST_VERSION_MIPI1 << OST_FIELD_PROTOCOL) | \
+ (OST_CONTROL_PROTOCOL << OST_FIELD_PROTOCOL))
+
+#define STM_MAKE_VERSION(ma, mi) (((ma) << 8) | (mi))
+#define STM_HEADER_MAGIC (0x5953)
+
+enum ost_entity_type {
+ OST_ENTITY_TYPE_NONE,
+ OST_ENTITY_TYPE_FTRACE,
+ OST_ENTITY_TYPE_CONSOLE,
+ OST_ENTITY_TYPE_DIAG,
+};
+
+static const char * const str_ost_entity_type[] = {
+ [OST_ENTITY_TYPE_NONE] = "none",
+ [OST_ENTITY_TYPE_FTRACE] = "ftrace",
+ [OST_ENTITY_TYPE_CONSOLE] = "console",
+ [OST_ENTITY_TYPE_DIAG] = "diag",
+};
+
+static const u32 ost_entity_value[] = {
+ [OST_ENTITY_TYPE_NONE] = 0,
+ [OST_ENTITY_TYPE_FTRACE] = OST_ENTITY_FTRACE,
+ [OST_ENTITY_TYPE_CONSOLE] = OST_ENTITY_CONSOLE,
+ [OST_ENTITY_TYPE_DIAG] = OST_ENTITY_DIAG,
+};
+
+struct ost_policy_node {
+ enum ost_entity_type entity_type;
+};
+
+struct ost_output {
+ struct ost_policy_node node;
+};
+
+/* Set default entity type as none */
+static void ost_policy_node_init(void *priv)
+{
+ struct ost_policy_node *pn = priv;
+
+ pn->entity_type = OST_ENTITY_TYPE_NONE;
+}
+
+static int ost_output_open(void *priv, struct stm_output *output)
+{
+ struct ost_policy_node *pn = priv;
+ struct ost_output *opriv;
+
+ opriv = kzalloc(sizeof(*opriv), GFP_ATOMIC);
+ if (!opriv)
+ return -ENOMEM;
+
+ memcpy(&opriv->node, pn, sizeof(opriv->node));
+ output->pdrv_private = opriv;
+ return 0;
+}
+
+static void ost_output_close(struct stm_output *output)
+{
+ kfree(output->pdrv_private);
+}
+
+static ssize_t ost_t_policy_entity_show(struct config_item *item,
+ char *page)
+{
+ ssize_t sz = 0;
+ int i;
+ struct ost_policy_node *pn = to_pdrv_policy_node(item);
+
+ for (i = 1; i < ARRAY_SIZE(str_ost_entity_type); i++) {
+ if (i == pn->entity_type)
+ sz += sysfs_emit_at(page, sz, "[%s] ", str_ost_entity_type[i]);
+ else
+ sz += sysfs_emit_at(page, sz, "%s ", str_ost_entity_type[i]);
+ }
+
+ sz += sysfs_emit_at(page, sz, "\n");
+ return sz;
+}
+
+static int entity_index(const char *str)
+{
+ int i;
+
+ for (i = 1; i < ARRAY_SIZE(str_ost_entity_type); i++) {
+ if (sysfs_streq(str, str_ost_entity_type[i]))
+ return i;
+ }
+
+ return 0;
+}
+
+static ssize_t
+ost_t_policy_entity_store(struct config_item *item, const char *page,
+ size_t count)
+{
+ struct ost_policy_node *pn = to_pdrv_policy_node(item);
+ int i;
+
+ i = entity_index(page);
+ if (i)
+ pn->entity_type = i;
+ else
+ return -EINVAL;
+
+ return count;
+}
+CONFIGFS_ATTR(ost_t_policy_, entity);
+
+static struct configfs_attribute *ost_t_policy_attrs[] = {
+ &ost_t_policy_attr_entity,
+ NULL,
+};
+
+static ssize_t
+notrace ost_write(struct stm_data *data, struct stm_output *output,
+ unsigned int chan, const char *buf, size_t count,
+ struct stm_source_data *source)
+{
+ unsigned int c = output->channel + chan;
+ unsigned int m = output->master;
+ const unsigned char nil = 0;
+ u32 header = DATA_HEADER;
+ struct trc_hdr {
+ u16 version;
+ u16 magic;
+ u32 cpu;
+ u64 timestamp;
+ u64 tgid;
+ } hdr;
+ ssize_t sz;
+ int i;
+ struct ost_output *op = output->pdrv_private;
+
+ /*
+ * Identify the source by entity type.
+ * If entity type is not set, return error value.
+ */
+ if (op->node.entity_type)
+ header |= ost_entity_value[op->node.entity_type];
+ else
+ return -EINVAL;
+
+ /*
+ * STP framing rules for OST frames:
+ * * the first packet of the OST frame is marked;
+ * * the last packet is a FLAG with timestamped tag.
+ */
+ /* Message layout: HEADER / DATA / TAIL */
+ /* HEADER */
+ sz = data->packet(data, m, c, STP_PACKET_DATA, STP_PACKET_MARKED,
+ 4, (u8 *)&header);
+ if (sz <= 0)
+ return sz;
+
+ /* DATA */
+ hdr.version = STM_MAKE_VERSION(0, 3);
+ hdr.magic = STM_HEADER_MAGIC;
+ hdr.cpu = raw_smp_processor_id();
+ hdr.timestamp = sched_clock();
+ hdr.tgid = task_tgid_nr(current);
+ sz = stm_data_write(data, m, c, false, &hdr, sizeof(hdr));
+ if (sz <= 0)
+ return sz;
+
+ sz = stm_data_write(data, m, c, false, buf, count);
+
+ /* TAIL */
+ if (sz > 0)
+ data->packet(data, m, c, STP_PACKET_FLAG,
+ STP_PACKET_TIMESTAMPED, 0, &nil);
+
+ return sz;
+}
+
+static const struct stm_protocol_driver ost_pdrv = {
+ .owner = THIS_MODULE,
+ .name = "p_ost",
+ .write = ost_write,
+ .policy_attr = ost_t_policy_attrs,
+ .output_open = ost_output_open,
+ .output_close = ost_output_close,
+ .policy_node_init = ost_policy_node_init,
+};
+
+static int ost_stm_init(void)
+{
+ return stm_register_protocol(&ost_pdrv);
+}
+module_init(ost_stm_init);
+
+static void ost_stm_exit(void)
+{
+ stm_unregister_protocol(&ost_pdrv);
+}
+module_exit(ost_stm_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("MIPI Open System Trace STM framing protocol driver");
--
2.43.0Hi Yingchao,
kernel test robot noticed the following build errors:
[auto build test ERROR on atorgue-stm32/stm32-next]
[also build test ERROR on linus/master v6.18-rc2 next-20251022]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Yingchao-Deng/stm-class-Add-MIPI-OST-protocol-support/20251022-152642
base: https://git.kernel.org/pub/scm/linux/kernel/git/atorgue/stm32.git stm32-next
patch link: https://lore.kernel.org/r/20251022071834.1658684-1-yingchao.deng%40oss.qualcomm.com
patch subject: [PATCH v3] stm: class: Add MIPI OST protocol support
config: m68k-allmodconfig (https://download.01.org/0day-ci/archive/20251023/202510231127.UFDSOpIQ-lkp@intel.com/config)
compiler: m68k-linux-gcc (GCC) 15.1.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251023/202510231127.UFDSOpIQ-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202510231127.UFDSOpIQ-lkp@intel.com/
All errors (new ones prefixed by >>):
drivers/hwtracing/stm/p_ost.c: In function 'ost_write':
>> drivers/hwtracing/stm/p_ost.c:201:27: error: implicit declaration of function 'task_tgid_nr' [-Wimplicit-function-declaration]
201 | hdr.tgid = task_tgid_nr(current);
| ^~~~~~~~~~~~
drivers/hwtracing/stm/p_ost.c:172:13: warning: unused variable 'i' [-Wunused-variable]
172 | int i;
| ^
vim +/task_tgid_nr +201 drivers/hwtracing/stm/p_ost.c
154
155 static ssize_t
156 notrace ost_write(struct stm_data *data, struct stm_output *output,
157 unsigned int chan, const char *buf, size_t count,
158 struct stm_source_data *source)
159 {
160 unsigned int c = output->channel + chan;
161 unsigned int m = output->master;
162 const unsigned char nil = 0;
163 u32 header = DATA_HEADER;
164 struct trc_hdr {
165 u16 version;
166 u16 magic;
167 u32 cpu;
168 u64 timestamp;
169 u64 tgid;
170 } hdr;
171 ssize_t sz;
172 int i;
173 struct ost_output *op = output->pdrv_private;
174
175 /*
176 * Identify the source by entity type.
177 * If entity type is not set, return error value.
178 */
179 if (op->node.entity_type)
180 header |= ost_entity_value[op->node.entity_type];
181 else
182 return -EINVAL;
183
184 /*
185 * STP framing rules for OST frames:
186 * * the first packet of the OST frame is marked;
187 * * the last packet is a FLAG with timestamped tag.
188 */
189 /* Message layout: HEADER / DATA / TAIL */
190 /* HEADER */
191 sz = data->packet(data, m, c, STP_PACKET_DATA, STP_PACKET_MARKED,
192 4, (u8 *)&header);
193 if (sz <= 0)
194 return sz;
195
196 /* DATA */
197 hdr.version = STM_MAKE_VERSION(0, 3);
198 hdr.magic = STM_HEADER_MAGIC;
199 hdr.cpu = raw_smp_processor_id();
200 hdr.timestamp = sched_clock();
> 201 hdr.tgid = task_tgid_nr(current);
202 sz = stm_data_write(data, m, c, false, &hdr, sizeof(hdr));
203 if (sz <= 0)
204 return sz;
205
206 sz = stm_data_write(data, m, c, false, buf, count);
207
208 /* TAIL */
209 if (sz > 0)
210 data->packet(data, m, c, STP_PACKET_FLAG,
211 STP_PACKET_TIMESTAMPED, 0, &nil);
212
213 return sz;
214 }
215
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
Hi Yingchao,
kernel test robot noticed the following build errors:
[auto build test ERROR on atorgue-stm32/stm32-next]
[also build test ERROR on linus/master v6.18-rc2 next-20251022]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Yingchao-Deng/stm-class-Add-MIPI-OST-protocol-support/20251022-152642
base: https://git.kernel.org/pub/scm/linux/kernel/git/atorgue/stm32.git stm32-next
patch link: https://lore.kernel.org/r/20251022071834.1658684-1-yingchao.deng%40oss.qualcomm.com
patch subject: [PATCH v3] stm: class: Add MIPI OST protocol support
config: i386-randconfig-013-20251023 (https://download.01.org/0day-ci/archive/20251023/202510230717.u8tTLt9x-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251023/202510230717.u8tTLt9x-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202510230717.u8tTLt9x-lkp@intel.com/
All errors (new ones prefixed by >>):
>> drivers/hwtracing/stm/p_ost.c:201:13: error: call to undeclared function 'task_tgid_nr'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
201 | hdr.tgid = task_tgid_nr(current);
| ^
drivers/hwtracing/stm/p_ost.c:172:6: warning: unused variable 'i' [-Wunused-variable]
172 | int i;
| ^
1 warning and 1 error generated.
vim +/task_tgid_nr +201 drivers/hwtracing/stm/p_ost.c
154
155 static ssize_t
156 notrace ost_write(struct stm_data *data, struct stm_output *output,
157 unsigned int chan, const char *buf, size_t count,
158 struct stm_source_data *source)
159 {
160 unsigned int c = output->channel + chan;
161 unsigned int m = output->master;
162 const unsigned char nil = 0;
163 u32 header = DATA_HEADER;
164 struct trc_hdr {
165 u16 version;
166 u16 magic;
167 u32 cpu;
168 u64 timestamp;
169 u64 tgid;
170 } hdr;
171 ssize_t sz;
172 int i;
173 struct ost_output *op = output->pdrv_private;
174
175 /*
176 * Identify the source by entity type.
177 * If entity type is not set, return error value.
178 */
179 if (op->node.entity_type)
180 header |= ost_entity_value[op->node.entity_type];
181 else
182 return -EINVAL;
183
184 /*
185 * STP framing rules for OST frames:
186 * * the first packet of the OST frame is marked;
187 * * the last packet is a FLAG with timestamped tag.
188 */
189 /* Message layout: HEADER / DATA / TAIL */
190 /* HEADER */
191 sz = data->packet(data, m, c, STP_PACKET_DATA, STP_PACKET_MARKED,
192 4, (u8 *)&header);
193 if (sz <= 0)
194 return sz;
195
196 /* DATA */
197 hdr.version = STM_MAKE_VERSION(0, 3);
198 hdr.magic = STM_HEADER_MAGIC;
199 hdr.cpu = raw_smp_processor_id();
200 hdr.timestamp = sched_clock();
> 201 hdr.tgid = task_tgid_nr(current);
202 sz = stm_data_write(data, m, c, false, &hdr, sizeof(hdr));
203 if (sz <= 0)
204 return sz;
205
206 sz = stm_data_write(data, m, c, false, buf, count);
207
208 /* TAIL */
209 if (sz > 0)
210 data->packet(data, m, c, STP_PACKET_FLAG,
211 STP_PACKET_TIMESTAMPED, 0, &nil);
212
213 return sz;
214 }
215
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
Hi Yingchao,
kernel test robot noticed the following build warnings:
[auto build test WARNING on atorgue-stm32/stm32-next]
[also build test WARNING on linus/master v6.18-rc2 next-20251022]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Yingchao-Deng/stm-class-Add-MIPI-OST-protocol-support/20251022-152642
base: https://git.kernel.org/pub/scm/linux/kernel/git/atorgue/stm32.git stm32-next
patch link: https://lore.kernel.org/r/20251022071834.1658684-1-yingchao.deng%40oss.qualcomm.com
patch subject: [PATCH v3] stm: class: Add MIPI OST protocol support
config: x86_64-randconfig-071-20251023 (https://download.01.org/0day-ci/archive/20251023/202510230738.OD0OO0n6-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251023/202510230738.OD0OO0n6-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202510230738.OD0OO0n6-lkp@intel.com/
All warnings (new ones prefixed by >>):
>> drivers/hwtracing/stm/p_ost.c:172:6: warning: unused variable 'i' [-Wunused-variable]
172 | int i;
| ^
1 warning generated.
vim +/i +172 drivers/hwtracing/stm/p_ost.c
154
155 static ssize_t
156 notrace ost_write(struct stm_data *data, struct stm_output *output,
157 unsigned int chan, const char *buf, size_t count,
158 struct stm_source_data *source)
159 {
160 unsigned int c = output->channel + chan;
161 unsigned int m = output->master;
162 const unsigned char nil = 0;
163 u32 header = DATA_HEADER;
164 struct trc_hdr {
165 u16 version;
166 u16 magic;
167 u32 cpu;
168 u64 timestamp;
169 u64 tgid;
170 } hdr;
171 ssize_t sz;
> 172 int i;
173 struct ost_output *op = output->pdrv_private;
174
175 /*
176 * Identify the source by entity type.
177 * If entity type is not set, return error value.
178 */
179 if (op->node.entity_type)
180 header |= ost_entity_value[op->node.entity_type];
181 else
182 return -EINVAL;
183
184 /*
185 * STP framing rules for OST frames:
186 * * the first packet of the OST frame is marked;
187 * * the last packet is a FLAG with timestamped tag.
188 */
189 /* Message layout: HEADER / DATA / TAIL */
190 /* HEADER */
191 sz = data->packet(data, m, c, STP_PACKET_DATA, STP_PACKET_MARKED,
192 4, (u8 *)&header);
193 if (sz <= 0)
194 return sz;
195
196 /* DATA */
197 hdr.version = STM_MAKE_VERSION(0, 3);
198 hdr.magic = STM_HEADER_MAGIC;
199 hdr.cpu = raw_smp_processor_id();
200 hdr.timestamp = sched_clock();
201 hdr.tgid = task_tgid_nr(current);
202 sz = stm_data_write(data, m, c, false, &hdr, sizeof(hdr));
203 if (sz <= 0)
204 return sz;
205
206 sz = stm_data_write(data, m, c, false, buf, count);
207
208 /* TAIL */
209 if (sz > 0)
210 data->packet(data, m, c, STP_PACKET_FLAG,
211 STP_PACKET_TIMESTAMPED, 0, &nil);
212
213 return sz;
214 }
215
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