On Thu, 10 May 2007 15:45:54 +0200 Pierre Ossman <[EMAIL PROTECTED]> wrote:
> Haavard Skinnemoen wrote: > > > > What exactly makes this unreliable? This is done almost exactly the > > same way for SCSI. See drivers/scsi/scsi_wait_scan.c. > > > > I am not against the function of waiting for an initial scan, what I oppose is > using side effects to achieve that function. I do not want to take > responsibility for something that easily breaks because we use a kernel > subsystem for something it wasn't meant for. Ok, is there any better way to achieve the same this? As far as I can tell, mmc_remove_host() uses mmc_flush_scheduled_work() for the same purpose -- it ensures that scans that have already been started will have completed before the function continues. > That said, if there is a precedent for achieving this function a certain way, > I > might be convinced to let it in. I'll have a look at that scsi example. Thanks. > > I don't know about USB, but root=/dev/mmcblk0p1 used to work before > > 2.6.20 and it doesn't work anymore. Doesn't that make this a regression? > > > > Yes and no. It depends on if it was an official function, or just an effect of > how things currently were implemented. As far as I can see, it's the latter. > The > MMC layer goes through several steps that could very well get delayed or > happen > in parallel. So the fact that it happened to work the way you wanted it to was > sheer luck. I wouldn't call it luck. The way mmc_rescan() is implemented, any scans that are started before late_initcall time are completed before mmc_finish_detect() returns. The steps are all done synchronously in the workqueue function. And I never realized that using a block device as a parameter to the root= parameter could possibly be "unofficial" functionality...? Haavard - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
