On 2018/9/24 17:26, Jiri Kosina wrote:
On Thu, 13 Sep 2018, Jia-Ju Bai wrote:hid_alloc_report_buf() has to be called with GFP_ATOMIC in __hid_request(), because there are the following callchains leading to __hid_request() being an atomic context: picolcd_send_and_wait (acquire a spinlock) hid_hw_request __hid_request hid_alloc_report_buf(GFP_KERNEL) picolcd_reset (acquire a spinlock) hid_hw_request __hid_request hid_alloc_report_buf(GFP_KERNEL) lg4ff_play (acquire a spinlock) hid_hw_request __hid_request hid_alloc_report_buf(GFP_KERNEL) lg4ff_set_autocenter_ffex (acquire a spinlock) hid_hw_request __hid_request hid_alloc_report_buf(GFP_KERNEL)Hm, so it's always drivers calling out into core in atomic context. So either we take this, and put our bets on being able to allocate the buffer without sleeping,
In my opinion, I prefer this way. Best wishes, Jia-Ju Bai
or actually fix the few drivers (it's just lg4ff and picolcd at the end of the day) not to do that, and explicitly anotate __hid_request() with might_sleep(). Hmm? Thanks,
