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Message-ID: <20241016220634.1469153-1-anjali.k.kulkarni@oracle.com>
Date: Wed, 16 Oct 2024 15:06:31 -0700
From: Anjali Kulkarni <anjali.k.kulkarni@...cle.com>
To: davem@...emloft.net, Liam.Howlett@...cle.com
Cc: edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com, mingo@...hat.com,
peterz@...radead.org, juri.lelli@...hat.com,
vincent.guittot@...aro.org, dietmar.eggemann@....com,
rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
vschneid@...hat.com, jiri@...nulli.us, linux-kernel@...r.kernel.org,
netdev@...r.kernel.org, akpm@...ux-foundation.org, shuah@...nel.org,
linux-kselftest@...r.kernel.org, anjali.k.kulkarni@...cle.com,
peili.io@...cle.com
Subject: [PATCH net-next v3 0/3] Threads support in proc connector
Recently we committed a fix to allow processes to receive notifications for
non-zero exits via the process connector module. Commit is a4c9a56e6a2c.
However, for threads, when it does a pthread_exit(&exit_status) call, the
kernel is not aware of the exit status with which pthread_exit is called.
It is sent by child thread to the parent process, if it is waiting in
pthread_join(). Hence, for a thread exiting abnormally, kernel cannot
send notifications to any listening processes.
The exception to this is if the thread is sent a signal which it has not
handled, and dies along with it's process as a result; for eg. SIGSEGV or
SIGKILL. In this case, kernel is aware of the non-zero exit and sends a
notification for it.
For our use case, we cannot have parent wait in pthread_join, one of the
main reasons for this being that we do not want to track normal
pthread_exit(), which could be a very large number. We only want to be
notified of any abnormal exits. Hence, threads are created with
pthread_attr_t set to PTHREAD_CREATE_DETACHED.
To fix this problem, we add a new type PROC_CN_MCAST_NOTIFY to proc connector
API, which allows a thread to send it's exit status to kernel either when
it needs to call pthread_exit() with non-zero value to indicate some
error or from signal handler before pthread_exit().
We also need to filter packets with non-zero exit notifications futher
based on instances, which can be identified by task names. Hence, added a
comm field to the packet's struct proc_event, in which task->comm is
stored.
v2->v3 changes:
- Handled comment by Liam Howlett to set hdev to NULL and add comment on
it
- Handled comment by Liam Howlett to combine functions for deleting+get
and deleting into one.
- Handled comment by Liam Howlett to remove extern in the functions
defined in cn_hash_test.h
- Some nits by Liam Howlett fixed.
- Made threads.c automated, by having an exit.log file created by
proc_filter.c, which threads.c checks to see if the values reported
for thread exits are correct. This was for a comment by Liam Howlett to
make the tests automated.
- Added "comm" field to struct proc_event, to copy the task's name to
the packet to allow further filtering by packets.
v1->v2 changes:
- Handled comment by Peter Zijlstra to remove locking for PF_EXIT_NOTIFY
task->flags.
- Added error handling in thread.c
v->v1 changes:
- Handled comment by Simon Horman to remove unused err in cn_proc.c
- Handled comment by Simon Horman to make adata and key_display static
in cn_hash_test.c
Anjali Kulkarni (3):
connector/cn_proc: Add hash table for threads
connector/cn_proc: Kunit tests for threads hash table
connector/cn_proc: Selftest for threads
drivers/connector/Makefile | 2 +-
drivers/connector/cn_hash.c | 221 ++++++++++++++++++
drivers/connector/cn_proc.c | 62 ++++-
drivers/connector/connector.c | 75 +++++-
include/linux/connector.h | 35 +++
include/linux/sched.h | 2 +-
include/uapi/linux/cn_proc.h | 5 +-
lib/Kconfig.debug | 17 ++
lib/Makefile | 1 +
lib/cn_hash_test.c | 167 +++++++++++++
lib/cn_hash_test.h | 10 +
tools/testing/selftests/connector/Makefile | 23 +-
.../testing/selftests/connector/proc_filter.c | 34 ++-
tools/testing/selftests/connector/thread.c | 202 ++++++++++++++++
.../selftests/connector/thread_filter.c | 96 ++++++++
15 files changed, 937 insertions(+), 15 deletions(-)
create mode 100644 drivers/connector/cn_hash.c
create mode 100644 lib/cn_hash_test.c
create mode 100644 lib/cn_hash_test.h
create mode 100644 tools/testing/selftests/connector/thread.c
create mode 100644 tools/testing/selftests/connector/thread_filter.c
--
2.46.0
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