Hi, On 4/13/2017 1:37 PM, Alan Stern wrote: > This patch reworks the way f_mass_storage.c handles memory barriers > and synchronization: > > The driver now uses a wait_queue instead of doing its own > task-state manipulations (even though only one task will ever > use the wait_queue). > > The thread_wakeup_needed variable is removed. It was only a > source of trouble; although it was what the driver tested to > see whether it should wake up, what we really wanted to see > was whether a USB transfer had completed. > > All the explicit memory barriers scattered throughout the > driver are replaced by a few calls to smp_load_acquire() and > smp_store_release(). > > The inreq_busy and outreq_busy fields are removed. In their > place, the driver keeps track of the current I/O direction by > splitting BUF_STATE_BUSY into two states: BUF_STATE_SENDING > and BUF_STATE_RECEIVING. > > The buffer states are no longer protected by a lock. Mutual > exclusion isn't needed; the state is changed only by the > driver's main thread when it owns the buffer, and only by the > request completion routine when the gadget core owns the buffer. > > The do_write() and throw_away_data() routines were reorganized > to make efficient use of the new sleeping mechanism. This > resulted in the removal of one indentation level in those > routines, making the patch appear to be more more complicated > than it really is. > > In a few places, the driver allowed itself to be frozen although > it really shouldn't have (in the middle of executing a SCSI > command). Those places have been fixed. > > The logic in the exception handler for aborting transfers and > waiting for them to stop has been simplified. > > Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> > > --- > > > [as1824] > > > drivers/usb/gadget/function/f_mass_storage.c | 355 +++++++++++---------------- > drivers/usb/gadget/function/storage_common.h | 7 > 2 files changed, 156 insertions(+), 206 deletions(-) > I ran some stress tests against this patch series and found no issue beside some trivial checkpatch complains. Kernel: 4.11-rc5 Driver: dwc3 Platform: HAPS-DX IP: USB 3.0 IP version 3.10a and USB 3.1 version 1.60a System: x86_64 Tested-by: Thinh Nguyen <thinhn@xxxxxxxxxxxx> BR, Thinh Nguyen -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
