On 2018/9/5 16:29, Jiri Kosina wrote:
On Sat, 1 Sep 2018, Jia-Ju Bai wrote:The driver may sleep with holding a spinlock. The function call paths (from bottom to top) in Linux-4.16 are: [FUNC] hid_alloc_report_buf(GFP_KERNEL) drivers/hid/hid-core.c, 1435: hid_alloc_report_buf in __hid_request ./include/linux/hid.h, 1023: __hid_request in hid_hw_request drivers/hid/hid-picolcd_core.c, 111: hid_hw_request in picolcd_send_and_wait drivers/hid/hid-picolcd_core.c, 100: _raw_spin_lock_irqsave in picolcd_send_and_wait [FUNC] hid_alloc_report_buf(GFP_KERNEL) drivers/hid/hid-core.c, 1435: hid_alloc_report_buf in __hid_request ./include/linux/hid.h, 1023: __hid_request in hid_hw_request drivers/hid/hid-picolcd_core.c, 245: hid_hw_request in picolcd_reset drivers/hid/hid-picolcd_core.c, 235: _raw_spin_lock_irqsave in picolcd_reset [FUNC] hid_alloc_report_buf(GFP_KERNEL) drivers/hid/hid-core.c, 1435: hid_alloc_report_buf in __hid_request ./include/linux/hid.h, 1023: __hid_request in hid_hw_request drivers/hid/hid-picolcd_fb.c, 215: hid_hw_request in picolcd_fb_reset drivers/hid/hid-picolcd_fb.c, 206: _raw_spin_lock_irqsave in picolcd_fb_reset [FUNC] hid_alloc_report_buf(GFP_KERNEL) drivers/hid/hid-core.c, 1435: hid_alloc_report_buf in __hid_request ./include/linux/hid.h, 1023: __hid_request in hid_hw_request drivers/hid/hid-lg4ff.c, 465: hid_hw_request in lg4ff_play drivers/hid/hid-lg4ff.c, 441: _raw_spin_lock_irqsave in lg4ff_play To fix this bug, GFP_KERNEL is replaced with GFP_ATOMIC. This bug is found by my static analysis tool DSAC.Could you please rewrite the changelog so that it's human readable? The above is a bit hard to understand, I think something along the lines of "__hid_request() has to be allocating with GFP_ATOMIC because there are the following callchains leading to __hid_request() being an atomic context: ... a->b->c.._hid_request()" etc.
Okay, I will send a new patch. Best wishes, Jia-Ju Bai
