From: Sebastian Andrzej Siewior Date: Tue, 26 Mar 2019 18:31:54 +0100 Subject: [PATCH] powerpc/pseries/iommu: Use a locallock instead local_irq_save() Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.6/older/patches-5.6.4-rt3.tar.xz The locallock protects the per-CPU variable tce_page. The function attempts to allocate memory while tce_page is protected (by disabling interrupts). Use local_irq_save() instead of local_irq_disable(). Cc: stable-rt@vger.kernel.org Signed-off-by: Sebastian Andrzej Siewior --- arch/powerpc/platforms/pseries/iommu.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) --- a/arch/powerpc/platforms/pseries/iommu.c +++ b/arch/powerpc/platforms/pseries/iommu.c @@ -24,6 +24,7 @@ #include #include #include +#include #include #include #include @@ -177,6 +178,7 @@ static int tce_build_pSeriesLP(unsigned } static DEFINE_PER_CPU(__be64 *, tce_page); +static DEFINE_LOCAL_IRQ_LOCK(tcp_page_lock); static int tce_buildmulti_pSeriesLP(struct iommu_table *tbl, long tcenum, long npages, unsigned long uaddr, @@ -198,7 +200,8 @@ static int tce_buildmulti_pSeriesLP(stru direction, attrs); } - local_irq_save(flags); /* to protect tcep and the page behind it */ + /* to protect tcep and the page behind it */ + local_lock_irqsave(tcp_page_lock, flags); tcep = __this_cpu_read(tce_page); @@ -209,7 +212,7 @@ static int tce_buildmulti_pSeriesLP(stru tcep = (__be64 *)__get_free_page(GFP_ATOMIC); /* If allocation fails, fall back to the loop implementation */ if (!tcep) { - local_irq_restore(flags); + local_unlock_irqrestore(tcp_page_lock, flags); return tce_build_pSeriesLP(tbl->it_index, tcenum, tbl->it_page_shift, npages, uaddr, direction, attrs); @@ -244,7 +247,7 @@ static int tce_buildmulti_pSeriesLP(stru tcenum += limit; } while (npages > 0 && !rc); - local_irq_restore(flags); + local_unlock_irqrestore(tcp_page_lock, flags); if (unlikely(rc == H_NOT_ENOUGH_RESOURCES)) { ret = (int)rc; @@ -415,13 +418,14 @@ static int tce_setrange_multi_pSeriesLP( DMA_BIDIRECTIONAL, 0); } - local_irq_disable(); /* to protect tcep and the page behind it */ + /* to protect tcep and the page behind it */ + local_lock_irq(tcp_page_lock); tcep = __this_cpu_read(tce_page); if (!tcep) { tcep = (__be64 *)__get_free_page(GFP_ATOMIC); if (!tcep) { - local_irq_enable(); + local_unlock_irq(tcp_page_lock); return -ENOMEM; } __this_cpu_write(tce_page, tcep); @@ -467,7 +471,7 @@ static int tce_setrange_multi_pSeriesLP( /* error cleanup: caller will clear whole range */ - local_irq_enable(); + local_unlock_irq(tcp_page_lock); return rc; }