This patch-set removes the limitation in the driver's code that only a single process will have a file-descriptor of the device at any point of time.
This limitation needs to be removed because of two reasons: 1. Blocking multiple processes and trying to account them was stupid and doomed to fail. 2. The driver needs to support system management applications that just want to inquire about the device's status while a deep-learning application is also running and sending work to the device. With this patch-set, there can be unlimited number of open file-descriptors of the device by unlimited number of user space processes. Having said that, only a single process can submit work to the device, or do any change in the device itself via IOCTLs. All the processes can perform inqueries about the device using the INFO IOCTL. This is enforced by using an object called "context". The "context" object is created as part of the private data the driver saves per an open file-descriptor. For backward compatibility with existing user-space code, the "context" is created in a lazy way (it is created on the first call to an IOCTL). There can be only a single context per process, and only a single context on the entire device is considered "compute context". Only the FD which owns the "compute context" can call IOCTLs which require this context, such as command submissions, memory map, etc. Only when an FD is completely released, its context will be closed. It doesn't matter if the FD is duplicated or shared in user-space, as the driver will keep a single private data structure (and single context) per that FD. In addition, a context that was open as a "non-compute context" can be upgraded to a "compute context", if there isn't any other "compute context". This is because the application usually calls the INOF IOCTL before it calls other IOCTLs. Thanks, Oded Oded Gabbay (9): habanalabs: add handle field to context structure habanalabs: verify context is valid in IOCTLs habanalabs: create context in lazy mode habanalabs: don't change frequency if user context is valid habanalabs: maintain a list of file private data objects habanalabs: define user context as compute context habanalabs: protect only pointer dereference in hard-reset habanalabs: kill user process after CS rollback habanalabs: allow multiple processes to open FD drivers/misc/habanalabs/command_buffer.c | 6 + drivers/misc/habanalabs/command_submission.c | 12 ++ drivers/misc/habanalabs/context.c | 145 ++++++++++++++++--- drivers/misc/habanalabs/debugfs.c | 4 +- drivers/misc/habanalabs/device.c | 144 +++++++++--------- drivers/misc/habanalabs/goya/goya_hwmgr.c | 11 +- drivers/misc/habanalabs/habanalabs.h | 39 ++--- drivers/misc/habanalabs/habanalabs_drv.c | 54 ++----- drivers/misc/habanalabs/habanalabs_ioctl.c | 20 ++- drivers/misc/habanalabs/memory.c | 6 + 10 files changed, 285 insertions(+), 156 deletions(-) -- 2.17.1
