[CRIU] [PATCH 3/4] ipc/sysctl: c/r kernel.{msg_next_id, sem_next_id, shm_next_id}

[Pavel Tikhomirov]

On 07/13/2016 03:53 PM, Pavel Emelyanov wrote:
> On 07/04/2016 10:47 AM, Pavel Tikhomirov wrote:
>> These are only three left in ipc_kern_table which we haven't
>> checkpointed yet, I'm not sure if somebody really uses them
>> except criu, but to be consistent, beter not to change them
>> while c/r.
>>
>> *We have these sysctls writable in VZ7 CT.
>> https://jira.sw.ru/browse/PSBM-48397
>>
>> Signed-off-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
>> ---
>>  criu/ipc_ns.c        | 33 ++++++++++++++++++++++++++++++++-
>>  images/ipc-var.proto |  3 +++
>>  2 files changed, 35 insertions(+), 1 deletion(-)
>>
>> diff --git a/criu/ipc_ns.c b/criu/ipc_ns.c
>> index 02fb9a0..c75cfb5 100644
>> --- a/criu/ipc_ns.c
>> +++ b/criu/ipc_ns.c
>> @@ -313,6 +313,12 @@ static int ipc_sysctl_req(IpcVarEntry *e, int op)
>>  		{ "fs/mqueue/msgsize_default",	&e->mq_msgsize_default,	CTL_U32 },
>>  	};
>>
>> +	struct sysctl_req req_next[] = {
>> +		{ "kernel/msg_next_id", &e->msg_next_id, CTL_U32 },
>> +		{ "kernel/sem_next_id", &e->sem_next_id, CTL_U32 },
>> +		{ "kernel/shm_next_id", &e->shm_next_id, CTL_U32 },
>> +	};
>> +
>>  	int ret;
>>
>>  	ret = sysctl_op(req, ARRAY_SIZE(req), op, CLONE_NEWIPC);
>> @@ -324,8 +330,19 @@ static int ipc_sysctl_req(IpcVarEntry *e, int op)
>>  		return 0;
>>  	}
>>
>> -	return sysctl_op(req_mq, ARRAY_SIZE(req_mq) - (e->has_mq_msg_default ? 0 : 2),
>> +	ret = sysctl_op(req_mq, ARRAY_SIZE(req_mq) - (e->has_mq_msg_default ? 0 : 2),
>>  	                 op, CLONE_NEWIPC);
>> +	if (ret)
>> +		return ret;
>> +
>> +	/* Skip xxx_next_id which were -1 or haven't existed on dump */
>> +	if (e->has_msg_next_id && (ret = sysctl_op(&req_next[0], 1, op, CLONE_NEWIPC)))
>> +		return ret;
>> +	if (e->has_sem_next_id && (ret = sysctl_op(&req_next[1], 1, op, CLONE_NEWIPC)))
>> +		return ret;
>> +	if (e->has_shm_next_id && (ret = sysctl_op(&req_next[2], 1, op, CLONE_NEWIPC)))
>
> Can we do it in one call to sysctl_op?

We will have to create proper req array for all possible combinations of 
has_xxx_next_id, for (1,0,1) that don't look good from my POV.

>
>> +		return ret;
>> +	return 0;
>>  }
>>
>>  /*
>> @@ -421,6 +438,9 @@ static int dump_ipc_var(struct cr_img *img)
>>  		goto err;
>>  	var.has_mq_msg_default = true;
>>  	var.has_mq_msgsize_default = true;
>> +	var.has_msg_next_id = true;
>> +	var.has_sem_next_id = true;
>> +	var.has_shm_next_id = true;
>>
>>  	ret = ipc_sysctl_req(&var, CTL_READ);
>>  	if (ret < 0) {
>> @@ -428,6 +448,17 @@ static int dump_ipc_var(struct cr_img *img)
>>  		goto err;
>>  	}
>>
>> +	/*
>> +	 * One can not write to msg_next_xxx sysctls -1,
>> +	 * which is their initial value
>> +	 */
>> +	if (var.msg_next_id == -1)
>> +		var.has_msg_next_id = false;
>> +	if (var.sem_next_id == -1)
>> +		var.has_sem_next_id = false;
>> +	if (var.shm_next_id == -1)
>> +		var.has_shm_next_id = false;
>> +
>>  	ret = pb_write_one(img, &var, PB_IPC_VAR);
>>  	if (ret < 0) {
>>  		pr_err("Failed to write IPC variables\n");
>> diff --git a/images/ipc-var.proto b/images/ipc-var.proto
>> index 153b167..4fd8362 100644
>> --- a/images/ipc-var.proto
>> +++ b/images/ipc-var.proto
>> @@ -13,4 +13,7 @@ message ipc_var_entry {
>>  	required uint32			mq_msgsize_max		= 12;
>>  	optional uint32			mq_msg_default		= 13;
>>  	optional uint32			mq_msgsize_default	= 14;
>> +	optional uint32			msg_next_id		= 15;
>> +	optional uint32			sem_next_id		= 16;
>> +	optional uint32			shm_next_id		= 17;
>>  }
>>
>

-- 
Best regards, Tikhomirov Pavel
Software Developer, Virtuozzo.