The complex main_running/queue_main mechanism is peculiar to atari_NCR5380.c. It isn't SMP safe and offers little value given that the work queue already offers concurrency management. Remove this complexity to bring atari_NCR5380.c closer to NCR5380.c. It is not a good idea to call the information transfer state machine from queuecommand because, according to Documentation/scsi/scsi_mid_low_api.txt that could happen in soft irq context. Fix this. Signed-off-by: Finn Thain --- drivers/scsi/NCR5380.h | 1 drivers/scsi/atari_NCR5380.c | 80 +++---------------------------------------- 2 files changed, 6 insertions(+), 75 deletions(-) Index: linux/drivers/scsi/NCR5380.h =================================================================== --- linux.orig/drivers/scsi/NCR5380.h 2015-12-22 12:16:24.000000000 +1100 +++ linux/drivers/scsi/NCR5380.h 2015-12-22 12:16:25.000000000 +1100 @@ -262,7 +262,6 @@ struct NCR5380_hostdata { * transfer to handle chip overruns */ int retain_dma_intr; struct work_struct main_task; - volatile int main_running; #ifdef SUPPORT_TAGS struct tag_alloc TagAlloc[8][8]; /* 8 targets and 8 LUNs */ #endif Index: linux/drivers/scsi/atari_NCR5380.c =================================================================== --- linux.orig/drivers/scsi/atari_NCR5380.c 2015-12-22 12:16:23.000000000 +1100 +++ linux/drivers/scsi/atari_NCR5380.c 2015-12-22 12:16:25.000000000 +1100 @@ -602,36 +602,6 @@ static void NCR5380_print_phase(struct S #endif -/* - * ++roman: New scheme of calling NCR5380_main() - * - * If we're not in an interrupt, we can call our main directly, it cannot be - * already running. Else, we queue it on a task queue, if not 'main_running' - * tells us that a lower level is already executing it. This way, - * 'main_running' needs not be protected in a special way. - * - * queue_main() is a utility function for putting our main onto the task - * queue, if main_running is false. It should be called only from a - * interrupt or bottom half. - */ - -#include -#include -#include - -static inline void queue_main(struct NCR5380_hostdata *hostdata) -{ - if (!hostdata->main_running) { - /* If in interrupt and NCR5380_main() not already running, - queue it on the 'immediate' task queue, to be processed - immediately after the current interrupt processing has - finished. */ - queue_work(hostdata->work_q, &hostdata->main_task); - } - /* else: nothing to do: the running NCR5380_main() will pick up - any newly queued command. */ -} - /** * NCR58380_info - report driver and host information * @instance: relevant scsi host instance @@ -714,8 +684,6 @@ static void __maybe_unused NCR5380_print hostdata = (struct NCR5380_hostdata *)instance->hostdata; local_irq_save(flags); - printk("NCR5380: coroutine is%s running.\n", - hostdata->main_running ? "" : "n't"); if (!hostdata->connected) printk("scsi%d: no currently connected command\n", HOSTNO); else @@ -757,8 +725,6 @@ static int __maybe_unused NCR5380_show_i hostdata = (struct NCR5380_hostdata *)instance->hostdata; local_irq_save(flags); - seq_printf(m, "NCR5380: coroutine is%s running.\n", - hostdata->main_running ? "" : "n't"); if (!hostdata->connected) seq_printf(m, "scsi%d: no currently connected command\n", HOSTNO); else @@ -997,17 +963,8 @@ static int NCR5380_queue_command(struct dprintk(NDEBUG_QUEUES, "scsi%d: command added to %s of queue\n", H_NO(cmd), (cmd->cmnd[0] == REQUEST_SENSE) ? "head" : "tail"); - /* If queue_command() is called from an interrupt (real one or bottom - * half), we let queue_main() do the job of taking care about main. If it - * is already running, this is a no-op, else main will be queued. - * - * If we're not in an interrupt, we can call NCR5380_main() - * unconditionally, because it cannot be already running. - */ - if (in_interrupt() || irqs_disabled()) - queue_main(hostdata); - else - NCR5380_main(&hostdata->main_task); + /* Kick off command processing */ + queue_work(hostdata->work_q, &hostdata->main_task); return 0; } @@ -1044,30 +1001,11 @@ static void NCR5380_main(struct work_str unsigned long flags; /* - * We run (with interrupts disabled) until we're sure that none of - * the host adapters have anything that can be done, at which point - * we set main_running to 0 and exit. - * - * Interrupts are enabled before doing various other internal - * instructions, after we've decided that we need to run through - * the loop again. - * - * this should prevent any race conditions. - * * ++roman: Just disabling the NCR interrupt isn't sufficient here, * because also a timer int can trigger an abort or reset, which can * alter queues and touch the Falcon lock. */ - /* Tell int handlers main() is now already executing. Note that - no races are possible here. If an int comes in before - 'main_running' is set here, and queues/executes main via the - task queue, it doesn't do any harm, just this instance of main - won't find any work left to do. */ - if (hostdata->main_running) - return; - hostdata->main_running = 1; - local_save_flags(flags); do { local_irq_disable(); /* Freeze request queues */ @@ -1182,11 +1120,6 @@ static void NCR5380_main(struct work_str done = 0; } } while (!done); - - /* Better allow ints _after_ 'main_running' has been cleared, else - an interrupt could believe we'll pick up the work it left for - us, but we won't see it anymore here... */ - hostdata->main_running = 0; local_irq_restore(flags); } @@ -1299,6 +1232,7 @@ static void NCR5380_dma_complete(struct static irqreturn_t NCR5380_intr(int irq, void *dev_id) { struct Scsi_Host *instance = dev_id; + struct NCR5380_hostdata *hostdata = shost_priv(instance); int done = 1, handled = 0; unsigned char basr; @@ -1367,11 +1301,9 @@ static irqreturn_t NCR5380_intr(int irq, #endif } - if (!done) { - dprintk(NDEBUG_INTR, "scsi%d: in int routine, calling main\n", HOSTNO); - /* Put a call to NCR5380_main() on the queue... */ - queue_main(shost_priv(instance)); - } + if (!done) + queue_work(hostdata->work_q, &hostdata->main_task); + return IRQ_RETVAL(handled); } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/