Attachment 48169 Details for Bug 34710 – Disable media polling if the kernel already does it

[patch] Disable media polling if the kernel already does it

0001-Bug-34710-CD-ROM-polling-failed-due-to-O_EXCL-flag.patch (text/plain), 4.37 KB, created by Martin Pitt on 2011-06-19 11:57:54 UTC

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Creator: Martin Pitt

Created: 2011-06-19 11:57:54 UTC

Size: 4.37 KB

patch

obsolete

>From 3db04360c659f6c09022676ad4b7067eecdecf83 Mon Sep 17 00:00:00 2001
>From: Martin Pitt <martin.pitt@ubuntu.com>
>Date: Sun, 19 Jun 2011 20:48:22 +0200
>Subject: [PATCH] =?UTF-8?q?Bug=2034710=20=E2=80=94=20CD-ROM=20polling=20fail?=
> =?UTF-8?q?ed=20due=20to=20O=5FEXCL=20flag?=
>MIME-Version: 1.0
>Content-Type: text/plain; charset=UTF-8
>Content-Transfer-Encoding: 8bit
>
>Newer kernels (2.6.38+) support in-kernel polling of CD-ROM/SD card devices.
>udev 172 and later enable this feature by default:
>
>  http://git.kernel.org/?p=linux/hotplug/udev.git;a=commitdiff;h=c5a41da949
>
>That will also handle the eject button properly and send out remove uevents,
>which causes stale mounts to be cleaned up properly.
>
>In-kernel polling avoids the userspace race conditions with accessing the
>drive.
>
>If kernel polling is not supported or enabled, fall back to the previous method
>of unlocking the CD drive door right after mounting, to keep the hardware
>button working.
>---
> src/device-private.h |    3 ++
> src/device.c         |    7 +++++-
> src/poller.c         |   55 ++++++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 64 insertions(+), 1 deletions(-)
>
>diff --git a/src/device-private.h b/src/device-private.h
>index a6db7f2..e519083 100644
>--- a/src/device-private.h
>+++ b/src/device-private.h
>@@ -59,6 +59,9 @@ struct DevicePrivate
>   gboolean job_is_cancellable;
>   double job_percentage;
> 
>+  gboolean checked_in_kernel_polling;
>+  gboolean using_in_kernel_polling;
>+
>   guint linux_md_poll_timeout_id;
> 
>   /* A list of current polling inhibitors (Inhibitor objects) */
>diff --git a/src/device.c b/src/device.c
>index b30fe1c..c4b4ab3 100644
>--- a/src/device.c
>+++ b/src/device.c
>@@ -6213,7 +6213,12 @@ filesystem_mount_completed_cb (DBusGMethodInvocation *context,
> 
>       update_info (device);
>       drain_pending_changes (device, FALSE);
>-      unlock_cd_tray (device);
>+      /* If the kernel and device support sending EJECT_REQUEST change uevents
>+       * and we use in-kernel polling, keep the door locked, as udev calls
>+       * eject on pressing the button.  Otherwise unlock it, to keep the
>+       * hardware button working without userspace support */
>+      if (!device->priv->using_in_kernel_polling)
>+        unlock_cd_tray (device);
> 
>       dbus_g_method_return (context, data->mount_point);
>     }
>diff --git a/src/poller.c b/src/poller.c
>index 9517b5d..cc807d8 100644
>--- a/src/poller.c
>+++ b/src/poller.c
>@@ -31,6 +31,7 @@
> #include <fcntl.h>
> #include <string.h>
> #include <errno.h>
>+#include <gudev/gudev.h>
> 
> #include "poller.h"
> #include "device.h"
>@@ -304,6 +305,52 @@ poller_setup (int argc,
> 
> /* ---------------------------------------------------------------------------------------------------- */
> 
>+static gboolean
>+check_in_kernel_polling (Device* d)
>+{
>+  /* only check once */
>+  if (!d->priv->checked_in_kernel_polling)
>+    {
>+      int poll_time;
>+      int fd;
>+      char c;
>+
>+      d->priv->checked_in_kernel_polling = TRUE;
>+
>+      poll_time = g_udev_device_get_sysfs_attr_as_int (d->priv->d, "events_poll_msecs");
>+#ifdef POLL_SHOW_DEBUG
>+      g_print("**** POLLER (%d): per-device poll time for %s: %i\n", getpid (), d->priv->device_file, poll_time);
>+#endif
>+
>+      if (poll_time >= 0)
>+	{
>+	  d->priv->using_in_kernel_polling = (poll_time > 0);
>+	  goto out;
>+	}
>+
>+      /* -1 means using global polling interval, so check the global default */
>+      /* check global default */
>+      fd = open("/sys/module/block/parameters/events_dfl_poll_msecs", O_RDONLY);
>+      if (fd > 0)
>+	{
>+	  if (read (fd, &c, 1) > 0)
>+	    {
>+#ifdef POLL_SHOW_DEBUG
>+	      g_print("**** POLLER (%d): global poll time first char: %c\n", getpid (), c);
>+#endif
>+	      /* if this is positive, we use in-kernel polling */
>+	      d->priv->using_in_kernel_polling = (c != '0' && c != '-');
>+	    }
>+	  close (fd);
>+	}
>+    }
>+
>+out:
>+  return d->priv->using_in_kernel_polling;
>+}
>+
>+/* ---------------------------------------------------------------------------------------------------- */
>+
> void
> poller_set_devices (GList *devices)
> {
>@@ -320,6 +367,14 @@ poller_set_devices (GList *devices)
>     {
>       Device *device = DEVICE (l->data);
> 
>+      if (check_in_kernel_polling (device))
>+	{
>+#ifdef POLL_SHOW_DEBUG
>+	  g_print("**** POLLER (%d): Kernel is polling %s already, ignoring\n", getpid (), device->priv->device_file);
>+#endif
>+	  continue;
>+	}
>+
>       device_array[n++] = device->priv->device_file;
>     }
> 
>-- 
>1.7.5.4
>

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Attachments on bug 34710: 43791 | 43798 | 43846 | 45212 | 45214 | 45215 | 45216 | 45307 | 45308 | 45319 | 47050 | 47051 | 47052 | 47053 | 47983 | 47984 | 47985 | 48169

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