powerpc/xive: make xive IPI allocation NULL-safe

__GFP_NOFAIL should not be used in new code [1].  xive_init_ipis()
allocates the xive_ipis array with __GFP_NOFAIL, which makes the
subsequent NULL check unreachable dead code.

Remove __GFP_NOFAIL so the allocation can fail, and make all xive_ipis
access paths NULL-safe:

- Return XIVE_BAD_IRQ from xive_ipi_cpu_to_irq() when xive_ipis is NULL.
- Set xive_ipis to NULL after kfree() in the error path to prevent
  use-after-free.
- Guard xive_setup_cpu_ipi() and xive_cleanup_cpu_ipi() against
  xive_ipi_irq == XIVE_BAD_IRQ to avoid dereferencing an uninitialized
  or already-freed xive_ipis array.

No functional change when allocation succeeds.

Link: https://lore.kernel.org/all/20260725202632.dcb325658896a470df91cf57@linux-foundation.org/ [1]
Fixes: 7dcc37b3eff9 ("powerpc/xive: Map one IPI interrupt per node")
Signed-off-by: Gou Hao <gouhao@uniontech.com>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Suggested-by: Cédric Le Goater <clg@kaod.org>
Suggested-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
Reviewed-by: Wentao Guan <guanwentao@uniontech.com>
Reviewed-by: jiazhenyuan <jiazhenyuan@uniontech.com>
Reviewed-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260727104215.184786-2-gouhao@uniontech.com

0 files changed, 0 insertions, 0 deletions