In case I wasn't clear... On 03/07, Oleg Nesterov wrote: > > On 03/07, Hillf Danton wrote: > > > > On Fri, 7 Mar 2025 11:54:56 +0530 K Prateek Nayak <kprateek.nayak@xxxxxxx> > > >> step-03 > > >> task-118766 new reader > > >> makes pipe empty > > > > > >Reader seeing a pipe full should wake up a writer allowing 118768 to > > >wakeup again and fill the pipe. Am I missing something? > > > > > Good catch, but that wakeup was cut off [2,3] Please note that "that wakeup" was _not_ removed by the patch below. "That wakeup" is another wakeup pipe_read() does before return: if (wake_writer) wake_up_interruptible_sync_poll(&pipe->wr_wait, ...); And wake_writer must be true if this reader changed the pipe_full() condition from T to F. Note also that pipe_read() won't sleep if it has read even one byte. > > [2] https://lore.kernel.org/lkml/20250304123457.GA25281@xxxxxxxxxx/ > > [3] https://lore.kernel.org/all/20250210114039.GA3588@xxxxxxxxxx/ > > Why do you think > > [PATCH v2 1/1] pipe: change pipe_write() to never add a zero-sized buffer > https://lore.kernel.org/all/20250210114039.GA3588@xxxxxxxxxx/ > > can make any difference ??? > > Where do you think a zero-sized buffer with ->len == 0 can come from? Oleg.
