From 47aeda7b70555049eccd7f020365aec031f41c62 Mon Sep 17 00:00:00 2001 From: Warner Losh Date: Fri, 23 Jul 2021 15:21:02 -0600 Subject: [PATCH] geom_disk: use a preallocated geom_event for disk destruction. Preallocate a geom_event (using the new geom_alloc_event) when we create a disk. When we create the disk, we're going to be in a sleepable context, so we can always allocate this extra bit of memory. Then use this preallocated memory to free the disk. CAM can try to free the disk from an unsleepable context if there was I/O outstanding when the disk was destroyted (say because the SIM said it had gone away). The I/O context isn't sleepable. Rather than trying to invent a retry mechanism and making sure all the other geom_disk consumers did it properly, preallocating the event ensure that the geom_disk will be properly torn down, even when there's memory pressure when the disk departs. Reviewd by: jhb Sponsored by: Netflix Differential Revision: https://reviews.freebsd.org/D30544 --- sys/geom/geom_disk.c | 5 ++++- sys/geom/geom_disk.h | 1 + 2 files changed, 5 insertions(+), 1 deletion(-) diff --git a/sys/geom/geom_disk.c b/sys/geom/geom_disk.c index fb215fb3dab..83d570f7e44 100644 --- a/sys/geom/geom_disk.c +++ b/sys/geom/geom_disk.c @@ -885,6 +885,7 @@ disk_create(struct disk *dp, int version) dp->d_sectorsize, DEVSTAT_ALL_SUPPORTED, DEVSTAT_TYPE_DIRECT, DEVSTAT_PRIORITY_MAX); dp->d_geom = NULL; + dp->d_event = g_alloc_event(M_WAITOK); dp->d_init_level = DISK_INIT_NONE; @@ -896,12 +897,14 @@ void disk_destroy(struct disk *dp) { + KASSERT(dp->d_event != NULL, + ("Disk destroy for %p with event NULL", dp)); disk_gone(dp); dp->d_destroyed = 1; g_cancel_event(dp); if (dp->d_devstat != NULL) devstat_remove_entry(dp->d_devstat); - g_post_event(g_disk_destroy, dp, M_WAITOK, NULL); + g_post_event_ep(g_disk_destroy, dp, dp->d_event, NULL); } void diff --git a/sys/geom/geom_disk.h b/sys/geom/geom_disk.h index 8e2282a09a3..7dd6e34c9ae 100644 --- a/sys/geom/geom_disk.h +++ b/sys/geom/geom_disk.h @@ -125,6 +125,7 @@ struct disk { /* Fields private to geom_disk, to be moved on next version bump */ LIST_HEAD(,disk_alias) d_aliases; + void *d_event; }; #define DISKFLAG_RESERVED 0x0001 /* Was NEEDSGIANT */