Remove PID namespaces support from restrack
cover Remove PID namespaces support from restrack
From: Leon Romanovsky <[email protected]>
Hi,
Please see individual commit messages for more details.
Thanks
Leon Romanovsky (2):
RDMA/restrack: Remove PID namespace support
RDMA/core: Check that process is still alive before sending it to the
users
drivers/infiniband/core/counters.c | 28 ++++++++----------- drivers/infiniband/core/nldev.c | 44 ++++++++++++++++-------------- drivers/infiniband/core/restrack.c | 20 +------------- drivers/infiniband/core/restrack.h | 1 - 4 files changed, 37 insertions(+), 56 deletions(-)
--
2.20.1
PATCH 1/2 RDMA/restrack: Remove PID namespace support
From: Leon Romanovsky <[email protected]>
IB resources are bounded to IB device and file descriptors, both entities are unaware to PID namespaces and to task lifetime.
The difference in model caused to unpredictable behavior for the following scenario:
1. Create FD and context
2. Share it with ephemeral child
3. Create any object and exit that child
The end result of this flow, that those newly created objects will be tracked by restrack, but won't be visible for users because task_struct associated with them already exited.
The right thing is to rely on net namespace only for any filtering purposes and drop PID namespace.
--- drivers/infiniband/core/counters.c | 14 -------------- drivers/infiniband/core/nldev.c | 13 +------------ drivers/infiniband/core/restrack.c | 20 +------------------- drivers/infiniband/core/restrack.h | 1 - 4 files changed, 2 insertions(+), 46 deletions(-)
drivers/infiniband/core/counters.c +0 -14
@@ -149,9 +149,6 @@ static bool auto_mode_match(struct ib_qp *qp, struct rdma_counter *counter,struct auto_mode_param *param = &counter->mode.param;bool match = true; -if (!rdma_is_visible_in_pid_ns (&qp->res)) -return false; -/* Ensure that counter belongs to the right PID */ if (task_pid_nr (counter->res.task) !=task_pid_nr (qp->res.task))return false;
@@ -229,9 +226,6 @@ static struct rdma_counter *rdma_get_counter_auto_mode(struct ib_qp *qp, rt = &dev->res[RDMA_RESTRACK_COUNTER ];xa_lock (&rt->xa);xa_for_each (&rt->xa, id, res) { -if (!rdma_is_visible_in_pid_ns (res)) -continue ; - counter = container_of(res, struct rdma_counter, res);if ((counter->device != qp->device) || (counter->port != port)) goto next;
@@ -412,9 +406,6 @@ static struct ib_qp *rdma_counter_get_qp(struct ib_device *dev, u32 qp_num)if (IS_ERR (res))return NULL ; -if (!rdma_is_visible_in_pid_ns (res)) - goto err; - qp = container_of(res, struct ib_qp, res);if (qp->qp_type ==IB_QPT_RAW_PACKET && !capable (CAP_NET_RAW )) goto err;
@@ -445,11 +436,6 @@ static struct rdma_counter *rdma_get_counter_by_id(struct ib_device *dev,if (IS_ERR (res))return NULL ; -if (!rdma_is_visible_in_pid_ns (res)) { -rdma_restrack_put (res); -return NULL ; - } - counter = container_of(res, struct rdma_counter, res);kref_get (&counter->kref);rdma_restrack_put (res);
drivers/infiniband/core/nldev.c +1 -12
@@ -698,9 +698,6 @@ static int fill_stat_counter_qps(struct sk_buff *msg, rt = &counter->device->res[RDMA_RESTRACK_QP ];xa_lock (&rt->xa);xa_for_each (&rt->xa, id, res) { -if (!rdma_is_visible_in_pid_ns (res)) -continue ; - qp = container_of(res, struct ib_qp, res);if (qp->qp_type ==IB_QPT_RAW_PACKET && !capable (CAP_NET_RAW ))continue ;
@@ -1222,15 +1219,10 @@ static int res_get_common_doit(struct sk_buff *skb, struct nlmsghdr *nlh, goto err; } -if (!rdma_is_visible_in_pid_ns (res)) { - ret = -ENOENT ; - goto err_get; - } - msg =nlmsg_new (NLMSG_DEFAULT_SIZE ,GFP_KERNEL );if (!msg) { ret = -ENOMEM ; - goto err; + goto err_get; } nlh = nlmsg_put(msg, NETLINK_CB(skb).portid, nlh->nlmsg_seq,
@@ -1334,9 +1326,6 @@ static int res_get_common_dumpit(struct sk_buff *skb,* objects. */ xa_for_each (&rt->xa, id, res) { -if (!rdma_is_visible_in_pid_ns (res)) -continue ; -if (idx < start || !rdma_restrack_get (res)) goto next;
drivers/infiniband/core/restrack.c +1 -19
@@ -116,11 +116,8 @@ int rdma_restrack_count(struct ib_device *dev, enum rdma_restrack_type type)u32 cnt =0 ;xa_lock (&rt->xa); -xas_for_each (&xas, e,U32_MAX ) { -if (!rdma_is_visible_in_pid_ns (e)) -continue ; +xas_for_each (&xas, e,U32_MAX ) cnt++; - }xa_unlock (&rt->xa);return cnt; }
@@ -346,18 +343,3 @@ void rdma_restrack_del(struct rdma_restrack_entry *res) } }EXPORT_SYMBOL (rdma_restrack_del); - -bool rdma_is_visible_in_pid_ns (struct rdma_restrack_entry *res) -{ -/* -* 1. Kern resources should be visible in init -* namespace only -* 2. Present only resources visible in the current -* namespace -*/ -if (rdma_is_kernel_res (res)) -return task_active_pid_ns (current) == &init_pid_ns; - -/* PID 0 means that resource is not found in current namespace */ -return task_pid_vnr (res->task); -}
drivers/infiniband/core/restrack.h +0 -1
@@ -27,5 +27,4 @@ int rdma_restrack_init(struct ib_device *dev);void rdma_restrack_clean (struct ib_device *dev);void rdma_restrack_attach_task (struct rdma_restrack_entry *res,struct task_struct *task); -bool rdma_is_visible_in_pid_ns (struct rdma_restrack_entry *res);#endif /* _RDMA_CORE_RESTRACK_H_ */
--
2.20.1
PATCH 2/2 RDMA/core: Check that process is still alive before sending it to the users
In reply to Leon RomanovskyFrom: Leon Romanovsky <[email protected]>
The PID information can disappear asynchronically because task can be killed and moved to zombie state. In such case, PID will be zero in similar way to the kernel tasks. Recognize such situation where we are asking to return orphaned object and simply skip filling PID attribute.
As part of this change, document the same scenario in counter.c code.
--- drivers/infiniband/core/counters.c | 14 ++++++++++++-- drivers/infiniband/core/nldev.c | 31 ++++++++++++++++++++++-------- 2 files changed, 35 insertions(+), 10 deletions(-)
drivers/infiniband/core/counters.c +12 -2
@@ -149,8 +149,18 @@ static bool auto_mode_match(struct ib_qp *qp, struct rdma_counter *counter,struct auto_mode_param *param = &counter->mode.param;bool match = true; -/* Ensure that counter belongs to the right PID */ -if (task_pid_nr (counter->res.task) !=task_pid_nr (qp->res.task)) +/* +* Ensure that counter belongs to the right PID. +* This operation can race with user space which kills +* the process and leaves QP and counters orphans. +* +* It is not a big deal because exitted task will leave both +* QP and counter in the same bucket of zombie process. Just ensure +* that process is still alive before procedding. +* +*/ +if (task_pid_nr (counter->res.task) !=task_pid_nr (qp->res.task) || + !task_pid_nr (qp->res.task))return false;if (auto_mask &RDMA_COUNTER_MASK_QP_TYPE )
drivers/infiniband/core/nldev.c +23 -8
@@ -399,20 +399,35 @@ static int fill_res_info(struct sk_buff *msg, struct ib_device *device)static int fill_res_name_pid (struct sk_buff *msg,struct rdma_restrack_entry *res) { +int err =0 ; +pid_t pid; +/* * For user resources, user is should read /proc/PID/comm to get the * name of the task file. */ if (rdma_is_kernel_res (res)) { -if (nla_put_string (msg,RDMA_NLDEV_ATTR_RES_KERN_NAME , - res->kern_name)) -return -EMSGSIZE ; - }else { -if (nla_put_u32 (msg,RDMA_NLDEV_ATTR_RES_PID , -task_pid_vnr (res->task))) -return -EMSGSIZE ; + err =nla_put_string (msg,RDMA_NLDEV_ATTR_RES_KERN_NAME , + res->kern_name); + goto out; } -return 0 ; + + pid =task_pid_vnr (res->task); +/* +* PID == 0 returns in two scenarios: +* 1. It is kernel task, but because we checked above, it won't be possible. +* 2. Task is dead and in zombie state. There is no need to print PID anymore. +*/ +if (pid) +/* +* This part is racy, task can be killed and PID will be zero right +* here but it is ok, next query won't return PID. We don't promise +* real-time reflection of SW objects. +*/ + err =nla_put_u32 (msg,RDMA_NLDEV_ATTR_RES_PID , pid); + +out: +return err ? -EMSGSIZE :0 ; } static bool fill_res_entry(struct ib_device *dev, struct sk_buff *msg,
--
2.20.1
RE: [PATCH rdma-next 2/2] RDMA/core: Check that process is still alive before sending it to the users
Quoted 89 lines
-----Original Message-----
From: [email protected] <linux-rdma- [email protected]> On Behalf Of Leon Romanovsky
Sent: Wednesday, October 2, 2019 7:33 AM
To: Doug Ledford <[email protected]>; Jason Gunthorpe <[email protected]>
Cc: Leon Romanovsky <[email protected]>; RDMA mailing list <linux- [email protected]>
Subject: [PATCH rdma-next 2/2] RDMA/core: Check that process is still alive before sending it to the usersFrom: Leon Romanovsky <[email protected]>
The PID information can disappear asynchronically because task can be killed and moved to zombie state. In such case, PID will be zero in similar way to the kernel tasks. Recognize such situation where we are asking to return orphaned object and simply skip filling PID attribute.
As part of this change, document the same scenario in
counter.ccode.Signed-off-by Leon Romanovsky <[email protected]>--- drivers/infiniband/core/counters.c | 14 ++++++++++++-- drivers/infiniband/core/nldev.c | 31 ++++++++++++++++++++++-------- 2 files changed, 35 insertions(+), 10 deletions(-)drivers/infiniband/core/counters.c +12
-2@@ -149,8 +149,18 @@ static bool auto_mode_match(struct ib_qp *qp, structrdma_counter *counter, struct auto_mode_param *param = &counter->mode.param;bool match = true; -/* Ensure that counter belongs to the right PID */ -if (task_pid_nr (counter->res.task) !=task_pid_nr (qp->res.task)) +/* +* Ensure that counter belongs to the right PID. +* This operation can race with user space which kills +* the process and leaves QP and counters orphans. +* +* It is not a big deal because exitted task will leave both +* QP and counter in the same bucket of zombie process. Just ensure +* that process is still alive before procedding. +* +*/ +if (task_pid_nr (counter->res.task) !=task_pid_nr (qp->res.task) || + !task_pid_nr (qp->res.task))return false;if (
auto_mask&RDMA_COUNTER_MASK_QP_TYPE) diff --gita/drivers/infiniband/core/nldev.cb/drivers/infiniband/core/nldev.cindex71bc08510064..c6fe0c52f6dc100644drivers/infiniband/core/nldev.c +11
-8@@ -399,20 +399,35 @@ static int fill_res_info(struct sk_buff *msg, struct ib_device *device) static int fill_res_name_pid(struct sk_buff *msg,struct rdma_restrack_entry *res) { +int err =0 ; +pid_t pid; +/* * For user resources, user is should read /proc/PID/comm to get the * name of the task file. */ if (rdma_is_kernel_res (res)) { -if (nla_put_string (msg,RDMA_NLDEV_ATTR_RES_KERN_NAME , - res->kern_name)) -return -EMSGSIZE ; - }else { -if (nla_put_u32 (msg,RDMA_NLDEV_ATTR_RES_PID , -task_pid_vnr (res->task))) -return -EMSGSIZE ; + err =nla_put_string (msg,RDMA_NLDEV_ATTR_RES_KERN_NAME , + res->kern_name); + goto out; } -return 0 ; + + pid =task_pid_vnr (res->task); +/* +* PID == 0 returns in two scenarios: +* 1. It is kernel task, but because we checked above, it won't be
Quoted 1 line
possible.
Please drop above comment point 1. See more below.
Quoted 8 lines
drivers/infiniband/core/nldev.c +1
-0+* 2. Task is dead and in zombie state. There is no need to print PID anymore.
drivers/infiniband/core/nldev.c +5
-0+*/ +if (pid) +/* +* This part is racy, task can be killed and PID will be zero right +* here but it is ok, next query won't return PID. We don't promise
drivers/infiniband/core/nldev.c static int fill_res_info(struct sk_buff *msg, struct ib_device *device) · line 431
Quoted 7 lines
drivers/infiniband/core/nldev.c +6
-0+* real-time reflection of SW objects. +*/ + err =nla_put_u32 (msg,RDMA_NLDEV_ATTR_RES_PID , pid); + +out: +return err ? -EMSGSIZE :0 ; }
Below code reads better along with rest of the comments in the patch.
if (kern_resource) {
err = nla_put_string(msg, RDMA_NLDEV_ATTR_RES_KERN_NAME,
res->kern_name);
} else {
pid_t pid;
pid = task_pid_vnr(res->task);
if (pid)
err = nla_put_u32(msg, RDMA_NLDEV_ATTR_RES_PID, pid);
}Quoted 4 lines
static bool fill_res_entry(struct
ib_device*dev, structsk_buff*msg,
--
2.20.1
Re: [PATCH rdma-next 2/2] RDMA/core: Check that process is still alive before sending it to the users
Quoted 110 lines · Parav Pandit
Quoted 89 lines
-----Original Message-----
From: [email protected] <linux-rdma- [email protected]> On Behalf Of Leon Romanovsky
Sent: Wednesday, October 2, 2019 7:33 AM
To: Doug Ledford <[email protected]>; Jason Gunthorpe <[email protected]>
Cc: Leon Romanovsky <[email protected]>; RDMA mailing list <linux- [email protected]>
Subject: [PATCH rdma-next 2/2] RDMA/core: Check that process is still alive before sending it to the usersFrom: Leon Romanovsky <[email protected]>
The PID information can disappear asynchronically because task can be killed and moved to zombie state. In such case, PID will be zero in similar way to the kernel tasks. Recognize such situation where we are asking to return orphaned object and simply skip filling PID attribute.
As part of this change, document the same scenario in
counter.ccode.Signed-off-by Leon Romanovsky <[email protected]>--- drivers/infiniband/core/counters.c | 14 ++++++++++++-- drivers/infiniband/core/nldev.c | 31 ++++++++++++++++++++++-------- 2 files changed, 35 insertions(+), 10 deletions(-)drivers/infiniband/core/counters.c +12
-2@@ -149,8 +149,18 @@ static bool auto_mode_match(struct ib_qp *qp, structrdma_counter *counter, struct auto_mode_param *param = &counter->mode.param;bool match = true; -/* Ensure that counter belongs to the right PID */ -if (task_pid_nr (counter->res.task) !=task_pid_nr (qp->res.task)) +/* +* Ensure that counter belongs to the right PID. +* This operation can race with user space which kills +* the process and leaves QP and counters orphans. +* +* It is not a big deal because exitted task will leave both +* QP and counter in the same bucket of zombie process. Just ensure +* that process is still alive before procedding. +* +*/ +if (task_pid_nr (counter->res.task) !=task_pid_nr (qp->res.task) || + !task_pid_nr (qp->res.task))return false;if (
auto_mask&RDMA_COUNTER_MASK_QP_TYPE) diff --gita/drivers/infiniband/core/nldev.cb/drivers/infiniband/core/nldev.cindex71bc08510064..c6fe0c52f6dc100644drivers/infiniband/core/nldev.c +11
-8@@ -399,20 +399,35 @@ static int fill_res_info(struct sk_buff *msg, struct ib_device *device) static int fill_res_name_pid(struct sk_buff *msg,struct rdma_restrack_entry *res) { +int err =0 ; +pid_t pid; +/* * For user resources, user is should read /proc/PID/comm to get the * name of the task file. */ if (rdma_is_kernel_res (res)) { -if (nla_put_string (msg,RDMA_NLDEV_ATTR_RES_KERN_NAME , - res->kern_name)) -return -EMSGSIZE ; - }else { -if (nla_put_u32 (msg,RDMA_NLDEV_ATTR_RES_PID , -task_pid_vnr (res->task))) -return -EMSGSIZE ; + err =nla_put_string (msg,RDMA_NLDEV_ATTR_RES_KERN_NAME , + res->kern_name); + goto out; } -return 0 ; + + pid =task_pid_vnr (res->task); +/* +* PID == 0 returns in two scenarios: +* 1. It is kernel task, but because we checked above, it won't be Quoted 1 line
possible.
Please drop above comment point 1. See more below.
Quoted 8 lines
drivers/infiniband/core/nldev.c +1
-0+* 2. Task is dead and in zombie state. There is no need to print PID anymore.
drivers/infiniband/core/nldev.c +5
-0+*/ +if (pid) +/* +* This part is racy, task can be killed and PID will be zero right +* here but it is ok, next query won't return PID. We don't promise
drivers/infiniband/core/nldev.c static int fill_res_info(struct sk_buff *msg, struct ib_device *device) · line 431
Quoted 7 lines
drivers/infiniband/core/nldev.c +6
-0+* real-time reflection of SW objects. +*/ + err =nla_put_u32 (msg,RDMA_NLDEV_ATTR_RES_PID , pid); + +out: +return err ? -EMSGSIZE :0 ; }Below code reads better along with rest of the comments in the patch.
Quoted 10 lines
if (kern_resource) {
err = nla_put_string(msg, RDMA_NLDEV_ATTR_RES_KERN_NAME,
res->kern_name);
} else {
pid_t pid;
pid = task_pid_vnr(res->task);
if (pid)
err = nla_put_u32(msg, RDMA_NLDEV_ATTR_RES_PID, pid);
}Why do you think that nested "if" reads better?
Thanks
Quoted 6 lines
Quoted 5 lines
static bool fill_res_entry(struct
ib_device*dev, structsk_buff*msg,
--
2.20.1
RE: [PATCH rdma-next 2/2] RDMA/core: Check that process is still alive before sending it to the users
Quoted 132 lines
-----Original Message-----
From: Leon Romanovsky <[email protected]>
Sent: Tuesday, October 8, 2019 2:52 AM
To: Parav Pandit <[email protected]>
Cc: Doug Ledford <[email protected]>; Jason Gunthorpe <[email protected]>; RDMA mailing list <[email protected]>
Subject: Re: [PATCH rdma-next 2/2] RDMA/core: Check that process is still alive before sending it to the usersQuoted 13 lines · Parav Pandit
Quoted 13 lines
-----Original Message-----
From: [email protected] <linux-rdma- [email protected]> On Behalf Of Leon Romanovsky
Sent: Wednesday, October 2, 2019 7:33 AM
To: Doug Ledford <[email protected]>; Jason Gunthorpe <[email protected]>
Cc: Leon Romanovsky <[email protected]>; RDMA mailing list <linux- [email protected]>
Subject: [PATCH rdma-next 2/2] RDMA/core: Check that process is still alive before sending it to the usersQuoted 6 lines
Quoted 6 lines
From: Leon Romanovsky <[email protected]>
The PID information can disappear asynchronically because task can be killed and moved to zombie state. In such case, PID will be zero in similar way to the kernel tasks. Recognize such situation where we are asking to return orphaned object and simply skip filling PID
attribute.
Quoted 35 lines
Quoted 35 lines
As part of this change, document the same scenario in
counter.ccode.Signed-off-by Leon Romanovsky <[email protected]>--- drivers/infiniband/core/counters.c | 14 ++++++++++++-- drivers/infiniband/core/nldev.c | 31 ++++++++++++++++++++++-------- 2 files changed, 35 insertions(+), 10 deletions(-)drivers/infiniband/core/counters.c +12
-2@@ -149,8 +149,18 @@ static bool auto_mode_match(struct ib_qp *qp,struct rdma_counter *counter, struct auto_mode_param *param = &counter->mode.param;bool match = true; -/* Ensure that counter belongs to the right PID */ -if (task_pid_nr (counter->res.task) !=task_pid_nr (qp->res.task)) +/* +* Ensure that counter belongs to the right PID. +* This operation can race with user space which kills +* the process and leaves QP and counters orphans. +* +* It is not a big deal because exitted task will leave both +* QP and counter in the same bucket of zombie process. Just ensure +* that process is still alive before procedding. +* +*/ +if (task_pid_nr (counter->res.task) !=task_pid_nr (qp->res.task) || + !task_pid_nr (qp->res.task))return false;Quoted 7 lines
Quoted 7 lines
if (
auto_mask&RDMA_COUNTER_MASK_QP_TYPE) diff --gita/drivers/infiniband/core/nldev.cb/drivers/infiniband/core/nldev.cindex71bc08510064..c6fe0c52f6dc100644drivers/infiniband/core/nldev.c +0
-0@@ -399,20 +399,35 @@ static int fill_res_info(struct sk_buff *msg,struct
ib_device*device) static int fill_res_name_pid(structsk_buff*msg,
Quoted 31 lines
Quoted 28 lines
drivers/infiniband/core/nldev.c +3
-1struct rdma_restrack_entry *res) { +int err =0 ; +pid_t pid; +/* * For user resources, user is should read /proc/PID/comm to get the * name of the task file. */ if (rdma_is_kernel_res (res)) { - if (nla_put_string(msg,
RDMA_NLDEV_ATTR_RES_KERN_NAME,drivers/infiniband/core/nldev.c +1
-6- res->kern_name)) -return -EMSGSIZE ; - }else { -if (nla_put_u32 (msg,RDMA_NLDEV_ATTR_RES_PID , -task_pid_vnr (res->task))) -return -EMSGSIZE ; + err = nla_put_string(msg,
RDMA_NLDEV_ATTR_RES_KERN_NAME,drivers/infiniband/core/nldev.c +7
-1+ res->kern_name); + goto out; } -return 0 ; + + pid =task_pid_vnr (res->task); +/* +* PID == 0 returns in two scenarios: +* 1. It is kernel task, but because we checked above, it won't be Quoted 1 line
possible.
Please drop above comment point 1. See more below.
Quoted 7 lines
drivers/infiniband/core/nldev.c static int fill_res_info(struct sk_buff *msg, struct ib_device *device)
Quoted 7 lines
drivers/infiniband/core/nldev.c +2
-0+ * 2. Task is dead and in zombie state. There is no need to print +PID anymore.
drivers/infiniband/core/nldev.c +4
-0+*/ +if (pid) +/* +* This part is racy, task can be killed and PID will be zero right
Quoted 18 lines
drivers/infiniband/core/nldev.c static int fill_res_info(struct sk_buff *msg, struct ib_device *device) · line 431
Quoted 9 lines
drivers/infiniband/core/nldev.c +1
-0+* here but it is ok, next query won't return PID. We don't promise
drivers/infiniband/core/nldev.c +6
-0+* real-time reflection of SW objects. +*/ + err =nla_put_u32 (msg,RDMA_NLDEV_ATTR_RES_PID , pid); + +out: +return err ? -EMSGSIZE :0 ; }Below code reads better along with rest of the comments in the patch.
if (kern_resource) { err = nla_put_string(msg, RDMA_NLDEV_ATTR_RES_KERN_NAME, res->kern_name); } else { pid_t pid;
Quoted 6 lines
Quoted 3 lines
pid = task_pid_vnr(res->task); if (pid) err = nla_put_u32(msg, RDMA_NLDEV_ATTR_RES_PID, pid); }Why do you think that nested "if" reads better?
Because pid access is required only for non-kernel resource.
Hence it shouldn't be called for kernel resource; it doesn't matter it return zero or not.
Re: [PATCH rdma-next 2/2] RDMA/core: Check that process is still alive before sending it to the users
In reply to Parav PanditQuoted 18 lines · Parav Pandit
Quoted 8 lines
(quoted diff) +1
-0+ * 2. Task is dead and in zombie state. There is no need to print PIDanymore.
drivers/infiniband/core/nldev.c +5
-0+*/ +if (pid) +/* +* This part is racy, task can be killed and PID will be zero right +* here but it is ok, next query won't return PID. We don't promise
drivers/infiniband/core/nldev.c static int fill_res_info(struct sk_buff *msg, struct ib_device *device) · line 431
Quoted 7 lines
drivers/infiniband/core/nldev.c +6
-0+* real-time reflection of SW objects. +*/ + err =nla_put_u32 (msg,RDMA_NLDEV_ATTR_RES_PID , pid); + +out: +return err ? -EMSGSIZE :0 ; }Below code reads better along with rest of the comments in the patch.
Quoted 10 lines
if (kern_resource) {
err = nla_put_string(msg, RDMA_NLDEV_ATTR_RES_KERN_NAME,
res->kern_name);
} else {
pid_t pid;
pid = task_pid_vnr(res->task);
if (pid)
err = nla_put_u32(msg, RDMA_NLDEV_ATTR_RES_PID, pid);
}I tend to agree, that the pid == 0 happens for !kernel is pretty indirect
Jason