On Thu, 2018-02-22 at 04:39 +0000, Bart Van Assche wrote:
On Thu, 2018-02-22 at 04:19 +0000, Damien Le Moal wrote:
It looks OK to me, at least if CONFIG_DEBUG_OBJECTS_RCU_HEAD is turned off since the init_rcu_head() and destroy_rcu_head() functions only care about that.
With rcu head debug turned on, I am not so sure. The object debug code will have references to unused rcu heads left behind for unused scsi cmds, which are indeed dynamically allocated for a device together with requests when the device is initialized, but they are never freed until the device is removed. So "dynamically allocated object", yes, but that does not match the use of the object done in scsi (i.e. alloc before use
- free after use).
Hello Damien,
Please have a look at the following part of Documentation/RCU/Design/Requirements/Requirements.html:
Similarly, statically allocated non-stack <tt>rcu_head</tt> structures must be initialized with <tt>init_rcu_head()</tt> and cleaned up with <tt>destroy_rcu_head()</tt>.
And from <linux/rcupdate.h>:
* rcu_head structures * allocated dynamically in the heap or defined statically don't need any * initialization.
Bart.