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author | David Woodhouse <dwmw@amazon.co.uk> | 2021-01-26 17:01:49 +0000 |
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committer | Juergen Gross <jgross@suse.com> | 2021-01-27 08:59:52 +0100 |
commit | 5f46400f7a6a4fad635d5a79e2aa5a04a30ffea1 (patch) | |
tree | 85b377d2b16d13a0b5d6583fa3ec14a908afa16c /drivers/xen/xenbus | |
parent | 0549cd67b01016b579047bce045b386202a8bcfc (diff) | |
download | linux-5f46400f7a6a4fad635d5a79e2aa5a04a30ffea1.tar.gz linux-5f46400f7a6a4fad635d5a79e2aa5a04a30ffea1.tar.bz2 linux-5f46400f7a6a4fad635d5a79e2aa5a04a30ffea1.zip |
xen: Fix XenStore initialisation for XS_LOCAL
In commit 3499ba8198ca ("xen: Fix event channel callback via INTX/GSI")
I reworked the triggering of xenbus_probe().
I tried to simplify things by taking out the workqueue based startup
triggered from wake_waiting(); the somewhat poorly named xenbus IRQ
handler.
I missed the fact that in the XS_LOCAL case (Dom0 starting its own
xenstored or xenstore-stubdom, which happens after the kernel is booted
completely), that IRQ-based trigger is still actually needed.
So... put it back, except more cleanly. By just spawning a xenbus_probe
thread which waits on xb_waitq and runs the probe the first time it
gets woken, just as the workqueue-based hack did.
This is actually a nicer approach for *all* the back ends with different
interrupt methods, and we can switch them all over to that without the
complex conditions for when to trigger it. But not in -rc6. This is
the minimal fix for the regression, although it's a step in the right
direction instead of doing a partial revert and actually putting the
workqueue back. It's also simpler than the workqueue.
Fixes: 3499ba8198ca ("xen: Fix event channel callback via INTX/GSI")
Reported-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/4c9af052a6e0f6485d1de43f2c38b1461996db99.camel@infradead.org
Signed-off-by: Juergen Gross <jgross@suse.com>
Diffstat (limited to 'drivers/xen/xenbus')
-rw-r--r-- | drivers/xen/xenbus/xenbus_probe.c | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c index c8f0282bb649..18ffd0551b54 100644 --- a/drivers/xen/xenbus/xenbus_probe.c +++ b/drivers/xen/xenbus/xenbus_probe.c @@ -714,6 +714,23 @@ static bool xs_hvm_defer_init_for_callback(void) #endif } +static int xenbus_probe_thread(void *unused) +{ + DEFINE_WAIT(w); + + /* + * We actually just want to wait for *any* trigger of xb_waitq, + * and run xenbus_probe() the moment it occurs. + */ + prepare_to_wait(&xb_waitq, &w, TASK_INTERRUPTIBLE); + schedule(); + finish_wait(&xb_waitq, &w); + + DPRINTK("probing"); + xenbus_probe(); + return 0; +} + static int __init xenbus_probe_initcall(void) { /* @@ -725,6 +742,20 @@ static int __init xenbus_probe_initcall(void) !xs_hvm_defer_init_for_callback())) xenbus_probe(); + /* + * For XS_LOCAL, spawn a thread which will wait for xenstored + * or a xenstore-stubdom to be started, then probe. It will be + * triggered when communication starts happening, by waiting + * on xb_waitq. + */ + if (xen_store_domain_type == XS_LOCAL) { + struct task_struct *probe_task; + + probe_task = kthread_run(xenbus_probe_thread, NULL, + "xenbus_probe"); + if (IS_ERR(probe_task)) + return PTR_ERR(probe_task); + } return 0; } device_initcall(xenbus_probe_initcall); |