Attachment 45933 Details for Bug 36394 – Take mode config lock for hotplug probe

[patch] Take mode config lock for hotplug probe

0001-drm-Take-lock-around-probes-for-drm_fb_helper_hotplu.patch (text/plain), 6.13 KB, created by Chris Wilson on 2011-04-22 02:58:12 UTC

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Creator: Chris Wilson

Created: 2011-04-22 02:58:12 UTC

Size: 6.13 KB

patch

obsolete

>From b430015b0d5d670b1b9525e5fdcbaeb26b8f5b70 Mon Sep 17 00:00:00 2001
>From: Chris Wilson <chris@chris-wilson.co.uk>
>Date: Fri, 22 Apr 2011 10:47:08 +0100
>Subject: [PATCH] drm: Take lock around probes for drm_fb_helper_hotplug_event
>
>We need to hold the dev->mode_config.mutex whilst detecting the output
>status. But we also need to drop it for the call into
>drm_fb_helper_single_fb_probe(), which indirectly acquires the lock when
>attaching the fbcon.
>
>Failure to do so exposes a race with normal output probing. Detected by
>adding some warnings that the mutex is held to the backend detect routines:
>
>[   17.772456] WARNING: at drivers/gpu/drm/i915/intel_crt.c:471 intel_crt_detect+0x3e/0x373 [i915]()
>[   17.772458] Hardware name: Latitude E6400
>[   17.772460] Modules linked in: kvm_intel kvm microcode uinput bridge stp xt_time xt_connlimit xt_realm iptable_raw xt_comment xt_recent xt_policy ipt_ULOG ipt_REJECT ipt_REDIRECT ipt_NETMAP ipt_MASQUERADE ipt_ECN ipt_ecn ipt_CLUSTERIP ipt_ah ipt_addrtype nf_nat_tftp nf_nat_snmp_basic nf_nat_sip nf_nat_pptp nf_nat_proto_gre nf_nat_irc nf_nat_h323 nf_nat_ftp nf_nat_amanda ts_kmp nf_conntrack_amanda nf_conntrack_sane nf_conntrack_tftp nf_conntrack_sip nf_conntrack_proto_sctp nf_conntrack_pptp nf_conntrack_proto_gre nf_conntrack_netlink nf_conntrack_netbios_ns nf_conntrack_irc nf_conntrack_h323 nf_conntrack_ftp xt_TPROXY nf_tproxy_core ip6_tables nf_defrag_ipv6 xt_tcpmss xt_pkttype xt_physdev xt_owner xt_NFQUEUE xt_NFLOG nfnetlink_log xt_multiport xt_mark xt_mac xt_limit xt_length xt_iprange xt_helper xt_hashlimit xt_DSCP xt_dscp xt_dccp xt_conntrack xt_connmark xt_CLASSIFY ipt_LOG xt_tcpudp xt_state iptable_nat nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_conntrack iptable_mangle nfnetlink iptable_filter ip_tables x_tables fuse nfsd nfs lockd fscache nfs_acl auth_rpcgss sunrpc xfs exportfs vhost_net macvtap macvlan tun loop firewire_sbp2 btusb bluetooth snd_hda_codec_hdmi snd_hda_codec_idt snd_hda_intel arc4 ecb snd_hda_codec i915 iwlagn snd_hwdep joydev drm_kms_helper snd_pcm drm iwlcore pcmcia snd_seq mac80211 snd_timer snd_seq_device cfg80211 snd dell_laptop i2c_i801 rfkill tpm_tis i2c_algo_bit soundcore yenta_socket i2c_core pcmcia_rsrc pcmcia_core dell_wmi sparse_keymap tpm evdev psmouse snd_page_alloc tpm_bios wmi video dcdbas serio_raw pcspkr battery ac power_supply button processor ext4 mbcache jbd2 crc16 dm_mod sg sd_mod sr_mod crc_t10dif cdrom usbhid hid uhci_hcd ahci libahci libata sdhci_pci ehci_hcd sdhci mmc_core scsi_mod firewire_ohci firewire_core usbcore crc_itu_t e1000e thermal thermal_sys nls_base [last unloaded: scsi_wait_scan]
>[   17.772582] Pid: 11, comm: kworker/0:1 Tainted: G        W 2.6.38.4-custom.2 #8
>[   17.772584] Call Trace:
>[   17.772591]  [<ffffffff81046af5>] ? warn_slowpath_common+0x78/0x8c
>[   17.772603]  [<ffffffffa03f3e5c>] ? intel_crt_detect+0x3e/0x373 [i915]
>[   17.772612]  [<ffffffffa0355d49>] ?  drm_helper_probe_single_connector_modes+0xbf/0x2af [drm_kms_helper]
>[   17.772619]  [<ffffffffa03534d5>] ?  drm_fb_helper_probe_connector_modes+0x39/0x4d [drm_kms_helper]
>[   17.772625]  [<ffffffffa0354760>] ?  drm_fb_helper_hotplug_event+0xa5/0xc3 [drm_kms_helper]
>[   17.772633]  [<ffffffffa035577f>] ? output_poll_execute+0x146/0x17c [drm_kms_helper]
>[   17.772638]  [<ffffffff81193c01>] ? cfq_init_queue+0x247/0x345
>[   17.772644]  [<ffffffffa0355639>] ? output_poll_execute+0x0/0x17c [drm_kms_helper]
>[   17.772648]  [<ffffffff8105b540>] ? process_one_work+0x193/0x28e
>[   17.772652]  [<ffffffff8105c6bc>] ? worker_thread+0xef/0x172
>[   17.772655]  [<ffffffff8105c5cd>] ? worker_thread+0x0/0x172
>[   17.772658]  [<ffffffff8105c5cd>] ? worker_thread+0x0/0x172
>[   17.772663]  [<ffffffff8105f767>] ? kthread+0x7a/0x82
>[   17.772668]  [<ffffffff8100a724>] ? kernel_thread_helper+0x4/0x10
>[   17.772671]  [<ffffffff8105f6ed>] ? kthread+0x0/0x82
>[   17.772674]  [<ffffffff8100a720>] ? kernel_thread_helper+0x0/0x10
>
>Reported-by:  Frederik Himpe <fhimpe@telenet.be>
>References: https://bugs.freedesktop.org/show_bug.cgi?id=36394
>Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
>---
> drivers/gpu/drm/drm_fb_helper.c |   27 +++++++++++++++++++++++----
> 1 files changed, 23 insertions(+), 4 deletions(-)
>
>diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
>index 11d7a72..32ddc3c 100644
>--- a/drivers/gpu/drm/drm_fb_helper.c
>+++ b/drivers/gpu/drm/drm_fb_helper.c
>@@ -1516,17 +1516,33 @@ bool drm_fb_helper_initial_config(struct drm_fb_helper *fb_helper, int bpp_sel)
> }
> EXPORT_SYMBOL(drm_fb_helper_initial_config);
> 
>-bool drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper)
>+/**
>+ * drm_fb_helper_hotplug_event - respond to a hotplug notification by
>+ *                               probing all the outputs attached to the fb.
>+ * @fb_helper: the drm_fb_helper
>+ *
>+ * LOCKING:
>+ * Called at runtime, must take mode config lock.
>+ *
>+ * Scan the CRTCs and connectors and try to put together a setup after
>+ * notification of a change in output configuration.
>+ *
>+ * RETURNS:
>+ * 0 on success and a non-zero error code otherwise.
>+ */
>+int drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper)
> {
>+	struct drm_device *dev = fb_helper->dev;;
> 	int count = 0;
> 	u32 max_width, max_height, bpp_sel;
> 	bool bound = false, crtcs_bound = false;
> 	struct drm_crtc *crtc;
> 
> 	if (!fb_helper->fb)
>-		return false;
>+		return 0;
> 
>-	list_for_each_entry(crtc, &fb_helper->dev->mode_config.crtc_list, head) {
>+	mutex_lock(&dev->mode_config.mutex);
>+	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
> 		if (crtc->fb)
> 			crtcs_bound = true;
> 		if (crtc->fb == fb_helper->fb)
>@@ -1535,7 +1551,8 @@ bool drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper)
> 
> 	if (!bound && crtcs_bound) {
> 		fb_helper->delayed_hotplug = true;
>-		return false;
>+		mutex_unlock(&dev->mode_config.mutex);
>+		return 0;
> 	}
> 	DRM_DEBUG_KMS("\n");
> 
>@@ -1546,8 +1563,10 @@ bool drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper)
> 	count = drm_fb_helper_probe_connector_modes(fb_helper, max_width,
> 						    max_height);
> 	drm_setup_crtcs(fb_helper);
>+	mutex_unlock(&dev->mode_config.mutex);
> 
> 	return drm_fb_helper_single_fb_probe(fb_helper, bpp_sel);
>+
> }
> EXPORT_SYMBOL(drm_fb_helper_hotplug_event);
> 
>-- 
>1.7.4.1
>

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Attachments on bug 36394: 45814 | 45832 | 45932 | 45933 | 45936 | 45946

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