ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 299 insertions, 0 deletions

diff --git a/fs/xfs/scrub/rtbitmap.c b/fs/xfs/scrub/rtbitmap.c
new file mode 100644
index 000000000..52c24d3d4
--- /dev/null
+++ b/fs/xfs/scrub/rtbitmap.c
@@ -0,0 +1,299 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2017-2023 Oracle.  All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@kernel.org>
+ */
+#include "xfs_platform.h"
+#include "xfs_fs.h"
+#include "xfs_shared.h"
+#include "xfs_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_mount.h"
+#include "xfs_btree.h"
+#include "xfs_log_format.h"
+#include "xfs_trans.h"
+#include "xfs_rtbitmap.h"
+#include "xfs_inode.h"
+#include "xfs_bmap.h"
+#include "xfs_bit.h"
+#include "xfs_rtgroup.h"
+#include "xfs_sb.h"
+#include "xfs_rmap.h"
+#include "xfs_rtrmap_btree.h"
+#include "xfs_exchmaps.h"
+#include "xfs_zone_alloc.h"
+#include "scrub/scrub.h"
+#include "scrub/common.h"
+#include "scrub/repair.h"
+#include "scrub/tempexch.h"
+#include "scrub/rtbitmap.h"
+#include "scrub/btree.h"
+
+/* Set us up with the realtime metadata locked. */
+int
+xchk_setup_rtbitmap(
+	struct xfs_scrub	*sc)
+{
+	struct xfs_mount	*mp = sc->mp;
+	struct xchk_rtbitmap	*rtb;
+	int			error;
+
+	if (xchk_need_intent_drain(sc))
+		xchk_fsgates_enable(sc, XCHK_FSGATES_DRAIN);
+
+	rtb = kzalloc_flex(*rtb, words, xchk_rtbitmap_wordcnt(sc),
+			   XCHK_GFP_FLAGS);
+	if (!rtb)
+		return -ENOMEM;
+	sc->buf = rtb;
+	rtb->sc = sc;
+
+	error = xchk_rtgroup_init(sc, sc->sm->sm_agno, &sc->sr);
+	if (error)
+		return error;
+
+	if (xchk_could_repair(sc)) {
+		error = xrep_setup_rtbitmap(sc, rtb);
+		if (error)
+			return error;
+	}
+
+	error = xchk_trans_alloc(sc, rtb->resblks);
+	if (error)
+		return error;
+
+	error = xchk_install_live_inode(sc, rtg_bitmap(sc->sr.rtg));
+	if (error)
+		return error;
+
+	error = xchk_ino_dqattach(sc);
+	if (error)
+		return error;
+
+	error = xchk_rtgroup_lock(sc, &sc->sr, XCHK_RTGLOCK_ALL);
+	if (error)
+		return error;
+
+	/*
+	 * Now that we've locked the rtbitmap, we can't race with growfsrt
+	 * trying to expand the bitmap or change the size of the rt volume.
+	 * Hence it is safe to compute and check the geometry values.
+	 */
+	if (mp->m_sb.sb_rblocks) {
+		rtb->rextents = xfs_blen_to_rtbxlen(mp, mp->m_sb.sb_rblocks);
+		rtb->rextslog = xfs_compute_rextslog(rtb->rextents);
+		rtb->rbmblocks = xfs_rtbitmap_blockcount(mp);
+	}
+
+	return 0;
+}
+
+/* Per-rtgroup bitmap contents. */
+
+/* Cross-reference rtbitmap entries with other metadata. */
+STATIC void
+xchk_rtbitmap_xref(
+	struct xchk_rtbitmap	*rtb,
+	xfs_rtblock_t		startblock,
+	xfs_rtblock_t		blockcount)
+{
+	struct xfs_scrub	*sc = rtb->sc;
+	xfs_rgblock_t		rgbno = xfs_rtb_to_rgbno(sc->mp, startblock);
+
+	if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
+		return;
+	if (!sc->sr.rmap_cur)
+		return;
+
+	xchk_xref_has_no_rt_owner(sc, rgbno, blockcount);
+	xchk_xref_is_not_rt_shared(sc, rgbno, blockcount);
+	xchk_xref_is_not_rt_cow_staging(sc, rgbno, blockcount);
+
+	if (rtb->next_free_rgbno < rgbno)
+		xchk_xref_has_rt_owner(sc, rtb->next_free_rgbno,
+				rgbno - rtb->next_free_rgbno);
+	rtb->next_free_rgbno = rgbno + blockcount;
+}
+
+/* Scrub a free extent record from the realtime bitmap. */
+STATIC int
+xchk_rtbitmap_rec(
+	struct xfs_rtgroup	*rtg,
+	struct xfs_trans	*tp,
+	const struct xfs_rtalloc_rec *rec,
+	void			*priv)
+{
+	struct xchk_rtbitmap	*rtb = priv;
+	struct xfs_scrub	*sc = rtb->sc;
+	xfs_rtblock_t		startblock;
+	xfs_filblks_t		blockcount;
+
+	startblock = xfs_rtx_to_rtb(rtg, rec->ar_startext);
+	blockcount = xfs_rtxlen_to_extlen(rtg_mount(rtg), rec->ar_extcount);
+
+	if (!xfs_verify_rtbext(rtg_mount(rtg), startblock, blockcount))
+		xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, 0);
+
+	xchk_rtbitmap_xref(rtb, startblock, blockcount);
+
+	if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
+		return -ECANCELED;
+
+	return 0;
+}
+
+/* Make sure the entire rtbitmap file is mapped with written extents. */
+STATIC int
+xchk_rtbitmap_check_extents(
+	struct xfs_scrub	*sc)
+{
+	struct xfs_bmbt_irec	map;
+	struct xfs_iext_cursor	icur;
+	struct xfs_mount	*mp = sc->mp;
+	struct xfs_inode	*ip = sc->ip;
+	xfs_fileoff_t		off = 0;
+	xfs_fileoff_t		endoff;
+	int			error = 0;
+
+	/* Mappings may not cross or lie beyond EOF. */
+	endoff = XFS_B_TO_FSB(mp, ip->i_disk_size);
+	if (xfs_iext_lookup_extent(ip, &ip->i_df, endoff, &icur, &map)) {
+		xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, endoff);
+		return 0;
+	}
+
+	while (off < endoff) {
+		int		nmap = 1;
+
+		if (xchk_should_terminate(sc, &error) ||
+		    (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT))
+			break;
+
+		/* Make sure we have a written extent. */
+		error = xfs_bmapi_read(ip, off, endoff - off, &map, &nmap,
+				XFS_DATA_FORK);
+		if (!xchk_fblock_process_error(sc, XFS_DATA_FORK, off, &error))
+			break;
+
+		if (nmap != 1 || !xfs_bmap_is_written_extent(&map)) {
+			xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, off);
+			break;
+		}
+
+		off += map.br_blockcount;
+	}
+
+	return error;
+}
+
+/* Scrub this group's realtime bitmap. */
+int
+xchk_rtbitmap(
+	struct xfs_scrub	*sc)
+{
+	struct xfs_mount	*mp = sc->mp;
+	struct xfs_rtgroup	*rtg = sc->sr.rtg;
+	struct xfs_inode	*rbmip = rtg_bitmap(rtg);
+	struct xchk_rtbitmap	*rtb = sc->buf;
+	xfs_rgblock_t		last_rgbno;
+	int			error;
+
+	/* Is sb_rextents correct? */
+	if (mp->m_sb.sb_rextents != rtb->rextents) {
+		xchk_ip_set_corrupt(sc, rbmip);
+		return 0;
+	}
+
+	/* Is sb_rextslog correct? */
+	if (mp->m_sb.sb_rextslog != rtb->rextslog) {
+		xchk_ip_set_corrupt(sc, rbmip);
+		return 0;
+	}
+
+	/*
+	 * Is sb_rbmblocks large enough to handle the current rt volume?  In no
+	 * case can we exceed 4bn bitmap blocks since the super field is a u32.
+	 */
+	if (rtb->rbmblocks > U32_MAX) {
+		xchk_ip_set_corrupt(sc, rbmip);
+		return 0;
+	}
+	if (mp->m_sb.sb_rbmblocks != rtb->rbmblocks) {
+		xchk_ip_set_corrupt(sc, rbmip);
+		return 0;
+	}
+
+	/* The bitmap file length must be aligned to an fsblock. */
+	if (rbmip->i_disk_size & mp->m_blockmask) {
+		xchk_ip_set_corrupt(sc, rbmip);
+		return 0;
+	}
+
+	/*
+	 * Is the bitmap file itself large enough to handle the rt volume?
+	 * growfsrt expands the bitmap file before updating sb_rextents, so the
+	 * file can be larger than sb_rbmblocks.
+	 */
+	if (rbmip->i_disk_size < XFS_FSB_TO_B(mp, rtb->rbmblocks)) {
+		xchk_ip_set_corrupt(sc, rbmip);
+		return 0;
+	}
+
+	/* Invoke the fork scrubber. */
+	error = xchk_metadata_inode_forks(sc);
+	if (error || (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT))
+		return error;
+
+	error = xchk_rtbitmap_check_extents(sc);
+	if (error || (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT))
+		return error;
+
+	rtb->next_free_rgbno = 0;
+	error = xfs_rtalloc_query_all(rtg, sc->tp, xchk_rtbitmap_rec, rtb);
+	if (!xchk_fblock_process_error(sc, XFS_DATA_FORK, 0, &error))
+		return error;
+
+	/*
+	 * Check that the are rmappings for all rt extents between the end of
+	 * the last free extent we saw and the last possible extent in the rt
+	 * group.
+	 */
+	last_rgbno = rtg->rtg_extents * mp->m_sb.sb_rextsize;
+	if (rtb->next_free_rgbno < last_rgbno)
+		xchk_xref_has_rt_owner(sc, rtb->next_free_rgbno,
+				last_rgbno - rtb->next_free_rgbno);
+	return 0;
+}
+
+/* xref check that the extent is not free in the rtbitmap */
+void
+xchk_xref_is_used_rt_space(
+	struct xfs_scrub	*sc,
+	xfs_rtblock_t		rtbno,
+	xfs_extlen_t		len)
+{
+	struct xfs_rtgroup	*rtg = sc->sr.rtg;
+	xfs_rtxnum_t		startext;
+	xfs_rtxnum_t		endext;
+	bool			is_free;
+	int			error;
+
+	if (xchk_skip_xref(sc->sm))
+		return;
+
+	if (xfs_has_zoned(sc->mp)) {
+		if (!xfs_zone_rgbno_is_valid(rtg,
+				xfs_rtb_to_rgbno(sc->mp, rtbno) + len - 1))
+			xchk_ip_xref_set_corrupt(sc, rtg_rmap(rtg));
+		return;
+	}
+
+	startext = xfs_rtb_to_rtx(sc->mp, rtbno);
+	endext = xfs_rtb_to_rtx(sc->mp, rtbno + len - 1);
+	error = xfs_rtalloc_extent_is_free(rtg, sc->tp, startext,
+			endext - startext + 1, &is_free);
+	if (!xchk_should_check_xref(sc, &error, NULL))
+		return;
+	if (is_free)
+		xchk_ip_xref_set_corrupt(sc, rtg_bitmap(rtg));
+}