powerpc/pseries: avoid blocking in irq when queuing hotplug events

A couple of bugs in queue_hotplug_event():

1. Unchecked kmalloc result which could lead to an oops.
2. Use of GFP_KERNEL allocations in interrupt context (this code's
   only caller is ras_hotplug_interrupt()).

Use kmemdup to avoid open-coding the allocation+copy and check for
failure; use GFP_ATOMIC for both allocations.

Ultimately it probably would be better to avoid or reduce allocations
in this path if possible.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/platforms/pseries/dlpar.c b/arch/powerpc/platforms/pseries/dlpar.c
index c852024044bb7dd7287b97a52d3681c31e89e6ba..4989c576239801389cdf3336ef1305201baa55ee 100644 (file)
--- a/arch/powerpc/platforms/pseries/dlpar.c
+++ b/arch/powerpc/platforms/pseries/dlpar.c
@@ -390,11 +390,11 @@ void queue_hotplug_event(struct pseries_hp_errorlog *hp_errlog)
        struct pseries_hp_work *work;
        struct pseries_hp_errorlog *hp_errlog_copy;
 
-       hp_errlog_copy = kmalloc(sizeof(struct pseries_hp_errorlog),
-                                GFP_KERNEL);
-       memcpy(hp_errlog_copy, hp_errlog, sizeof(struct pseries_hp_errorlog));
+       hp_errlog_copy = kmemdup(hp_errlog, sizeof(*hp_errlog), GFP_ATOMIC);
+       if (!hp_errlog_copy)
+               return;
 
-       work = kmalloc(sizeof(struct pseries_hp_work), GFP_KERNEL);
+       work = kmalloc(sizeof(struct pseries_hp_work), GFP_ATOMIC);
        if (work) {
                INIT_WORK((struct work_struct *)work, pseries_hp_work_fn);
                work->errlog = hp_errlog_copy;