On Mon, Aug 2, 2021 at 8:47 AM Leon Romanovsky [off-list ref] wrote:

On Fri, Jul 30, 2021 at 03:18:24PM +0200, Jack Wang wrote:

quoted

From: Gioh Kim <redacted>

If the client tries to create a path with name "ctl",
the server tries to creates /sys/devices/virtual/rtrs-server/ctl/.
Then server generated below error because there is already ctl directory
which manages some setup of the server.

sysfs: cannot create duplicate filename '/devices/virtual/rtrs-server/ctl'
Workqueue: ib-comp-wq ib_cq_poll_work [ib_core]
Call Trace:
dump_stack+0x50/0x63
sysfs_warn_dup.cold+0x17/0x24
sysfs_create_dir_ns+0xb6/0xd0
kobject_add_internal+0xa6/0x2a0
kobject_add+0x7e/0xb0
? _cond_resched+0x15/0x30
device_add+0x121/0x640
rtrs_srv_create_sess_files+0x18f/0x1f0 [rtrs_server]
? __alloc_pages_nodemask+0x16c/0x2b0
? kmalloc_order+0x7c/0x90
? kmalloc_order_trace+0x1d/0xa0
? rtrs_iu_alloc+0x17e/0x1bf [rtrs_core]
rtrs_srv_info_req_done+0x417/0x5b0 [rtrs_server]
? __switch_to_asm+0x40/0x70
__ib_process_cq+0x76/0xd0 [ib_core]
ib_cq_poll_work+0x26/0x80 [ib_core]
process_one_work+0x1df/0x3a0
worker_thread+0x4a/0x3c0
kthread+0xfb/0x130
? process_one_work+0x3a0/0x3a0
? kthread_park+0x90/0x90
ret_from_fork+0x1f/0x40
kobject_add_internal failed for ctl with -EEXIST, don't try to register things with the same name in the same directory.
rtrs_server L178: device_add(): -17

This patch checks the path name and disconnect on server to prevent
the kernel error.

Signed-off-by: Gioh Kim <redacted>
Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
---
 drivers/infiniband/ulp/rtrs/rtrs-srv.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/infiniband/ulp/rtrs/rtrs-srv.c b/drivers/infiniband/ulp/rtrs/rtrs-srv.c
index cd9a4ccf4c28..b814a6052cf1 100644
--- a/drivers/infiniband/ulp/rtrs/rtrs-srv.c
+++ b/drivers/infiniband/ulp/rtrs/rtrs-srv.c

@@ -758,6 +758,14 @@ static bool exist_sessname(struct rtrs_srv_ctx *ctx,
      struct rtrs_srv_sess *sess;
      bool found = false;

+     /*
+      * Session name "ct" is not allowed because
+      * /sys/devices/virtual/rtrs-server/ctl already exists
+      * for setup management.
+      */
+     if (!strcmp(sessname, "ctl"))
+             return true;

Why does it have special treatment?

rtrs-server creates a folder named ctl when the module is modprob'ed.
When a session is established, a folder of the session name is created
at the same location, which would hold sysfs entries such as
clt_hostname, path details, queue_depth, etc.

Due to this conflict of names, creation of session with that name is
not possible. So this gracefully fails the connection establishment
instead of a stack trace.

And what will happen if user supplies "." or ".."?

Weirdly enough, this succeeds. I tried, and the session creation
succeeds, and there is a hidden entry in the rtrs-server folder, but
it cannot be accessed through bash.

Does rtrs receive this session name from the other side in the network?

Yes. This string is entered by the user while creating the session.

Thanks