[RFC 00/12] powerpc/pseries,powernv: Enable clang context analysis

[RFC 00/12] powerpc/pseries,powernv: Enable clang context analysis

[Ritesh Harjani (IBM)]

Enable Clang context analysis checking for PowerPC pseries & powernv platforms.

Lock acquire and release checking used to be done with Sparse. That support was
removed [1] and replaced with Clang context analysis [2].

Note that enabling this caught few real locking races in arch/powerpc/mm.
However, the fixes for those and enablement for the rest of the subsystems will
be done in a follow up patch series. Also the more invasive checkers to check
what each lock protects is again deferred for later enablement.

The series was build tested with Clang 23.x

[1] 5b63d0ae94cc ("compiler-context-analysis: Remove Sparse support")
[2] 3269701cb256 ("compiler-context-analysis: Add infrastructure for Context Analysis with Clang")


Ritesh Harjani (IBM) (12):
  powerpc/pseries: Drop inline from hugepage invalidate
  powerpc/pseries: Rework hugepage invalidate to remove conditional locking
  powerpc/pseries: Rework hash flush to remove conditional locking
  powerpc/pseries: Add context annotations for the DTL worker lock
  powerpc/pseries: Annotate the VPD sequence lock context
  powerpc/pseries: Annotate the RTAS indices sequence lock context
  powerpc/pseries: Annotate the RTAS physical-attestation sequence lock context
  powerpc/pseries: Annotate the DTL debugfs read lock context
  powerpc/pseries: Disable context analysis for the CMM hotplug notifier
  powerpc/pseries: Enable context analysis
  powerpc/powernv: Rework OPAL console write to remove conditional locking
  powerpc/powernv: Enable context analysis

 arch/powerpc/platforms/powernv/Makefile       |  2 +
 arch/powerpc/platforms/powernv/opal.c         | 30 ++++++----
 arch/powerpc/platforms/pseries/Makefile       |  3 +
 arch/powerpc/platforms/pseries/cmm.c          |  1 +
 arch/powerpc/platforms/pseries/dtl.c          |  8 +++
 arch/powerpc/platforms/pseries/lpar.c         | 59 ++++++++++++-------
 arch/powerpc/platforms/pseries/papr-indices.c |  3 +
 .../platforms/pseries/papr-phy-attest.c       |  4 ++
 arch/powerpc/platforms/pseries/papr-vpd.c     |  3 +
 9 files changed, 81 insertions(+), 32 deletions(-)

--
2.39.5

[RFC 01/12] powerpc/pseries: Drop inline from hugepage invalidate

[Ritesh Harjani (IBM)]

Leave __pSeries_lpar_hugepage_invalidate() static and let the
compiler decide whether to inline it.

Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
---
 arch/powerpc/platforms/pseries/lpar.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
index 6a415febc53b..94cd30e9f6e1 100644
--- a/arch/powerpc/platforms/pseries/lpar.c
+++ b/arch/powerpc/platforms/pseries/lpar.c
@@ -1225,7 +1225,7 @@ static void hugepage_bulk_invalidate(unsigned long *slot, unsigned long *vpn,
 	}
 }
 
-static inline void __pSeries_lpar_hugepage_invalidate(unsigned long *slot,
+static void __pSeries_lpar_hugepage_invalidate(unsigned long *slot,
 						      unsigned long *vpn,
 						      int count, int psize,
 						      int ssize)
-- 
2.39.5

[RFC 02/12] powerpc/pseries: Rework hugepage invalidate to remove conditional locking

[Ritesh Harjani (IBM)]

Clang's compiler based static context analysis does not work with locks
that are conditionally taken like in __pSeries_lpar_hugepage_invalidate().

lpar.c:1240:6: error: spinlock 'pSeries_lpar_tlbie_lock' is not held on every path through here [-Werror,-Wthread-safety-analysis]

But this also simplifies the function definition in my opinion - so this
is also a win.

No functional change intended.

Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
---
 arch/powerpc/platforms/pseries/lpar.c | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
index 94cd30e9f6e1..abd77c45cbf4 100644
--- a/arch/powerpc/platforms/pseries/lpar.c
+++ b/arch/powerpc/platforms/pseries/lpar.c
@@ -1224,26 +1224,33 @@ static void hugepage_bulk_invalidate(unsigned long *slot, unsigned long *vpn,
 		BUG_ON(rc != H_SUCCESS);
 	}
 }
-
-static void __pSeries_lpar_hugepage_invalidate(unsigned long *slot,
+static void __pSeries_lpar_hugepage_invalidate_unlocked(unsigned long *slot,
 						      unsigned long *vpn,
 						      int count, int psize,
 						      int ssize)
 {
-	unsigned long flags = 0;
-	int lock_tlbie = !mmu_has_feature(MMU_FTR_LOCKLESS_TLBIE);
-
-	if (lock_tlbie)
-		spin_lock_irqsave(&pSeries_lpar_tlbie_lock, flags);
-
 	/* Assuming THP size is 16M */
 	if (is_supported_hlbkrm(psize, MMU_PAGE_16M))
 		hugepage_block_invalidate(slot, vpn, count, psize, ssize);
 	else
 		hugepage_bulk_invalidate(slot, vpn, count, psize, ssize);
+}
 
-	if (lock_tlbie)
+static void __pSeries_lpar_hugepage_invalidate(unsigned long *slot,
+						      unsigned long *vpn,
+						      int count, int psize,
+						      int ssize)
+{
+	unsigned long flags = 0;
+
+	if (!mmu_has_feature(MMU_FTR_LOCKLESS_TLBIE)) {
+		spin_lock_irqsave(&pSeries_lpar_tlbie_lock, flags);
+		__pSeries_lpar_hugepage_invalidate_unlocked(slot, vpn, count, psize, ssize);
 		spin_unlock_irqrestore(&pSeries_lpar_tlbie_lock, flags);
+		return;
+	}
+
+	__pSeries_lpar_hugepage_invalidate_unlocked(slot, vpn, count, psize, ssize);
 }
 
 static void pSeries_lpar_hugepage_invalidate(unsigned long vsid,
-- 
2.39.5

[RFC 03/12] powerpc/pseries: Rework hash flush to remove conditional locking

[Ritesh Harjani (IBM)]

Clang's compiler based static context analysis does not work with locks
that are conditionally taken like in pSeries_lpar_flush_hash_range().

This also simplifies the function definition in my opinion - so this
is also a win.

No functional change intended.

Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
---
 arch/powerpc/platforms/pseries/lpar.c | 31 ++++++++++++++++-----------
 1 file changed, 18 insertions(+), 13 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
index abd77c45cbf4..5dbf447d3a83 100644
--- a/arch/powerpc/platforms/pseries/lpar.c
+++ b/arch/powerpc/platforms/pseries/lpar.c
@@ -1526,28 +1526,19 @@ void __init pseries_lpar_read_hblkrm_characteristics(void)
 					bpsize, idx, hblkrm_size[bpsize][idx]);
 }
 
-/*
- * Take a spinlock around flushes to avoid bouncing the hypervisor tlbie
- * lock.
- */
-static void pSeries_lpar_flush_hash_range(unsigned long number, int local)
+static void pSeries_lpar_flush_hash_range_unlocked(unsigned long number, int local)
 {
 	unsigned long vpn;
 	unsigned long i, pix, rc;
-	unsigned long flags = 0;
 	struct ppc64_tlb_batch *batch = this_cpu_ptr(&ppc64_tlb_batch);
-	int lock_tlbie = !mmu_has_feature(MMU_FTR_LOCKLESS_TLBIE);
 	unsigned long param[PLPAR_HCALL9_BUFSIZE];
 	unsigned long index, shift, slot;
 	real_pte_t pte;
 	int psize, ssize;
 
-	if (lock_tlbie)
-		spin_lock_irqsave(&pSeries_lpar_tlbie_lock, flags);
-
 	if (is_supported_hlbkrm(batch->psize, batch->psize)) {
 		do_block_remove(number, batch, param);
-		goto out;
+		return;
 	}
 
 	psize = batch->psize;
@@ -1587,10 +1578,24 @@ static void pSeries_lpar_flush_hash_range(unsigned long number, int local)
 				  param[6], param[7]);
 		BUG_ON(rc != H_SUCCESS);
 	}
+}
 
-out:
-	if (lock_tlbie)
+/*
+ * Take a spinlock around flushes to avoid bouncing the hypervisor tlbie
+ * lock. Firmware with MMU_FTR_LOCKLESS_TLBIE does not need it.
+ */
+static void pSeries_lpar_flush_hash_range(unsigned long number, int local)
+{
+	unsigned long flags;
+
+	if (!mmu_has_feature(MMU_FTR_LOCKLESS_TLBIE)) {
+		spin_lock_irqsave(&pSeries_lpar_tlbie_lock, flags);
+		pSeries_lpar_flush_hash_range_unlocked(number, local);
 		spin_unlock_irqrestore(&pSeries_lpar_tlbie_lock, flags);
+		return;
+	}
+
+	pSeries_lpar_flush_hash_range_unlocked(number, local);
 }
 
 static int __init disable_bulk_remove(char *str)
-- 
2.39.5

[RFC 04/12] powerpc/pseries: Add context annotations for the DTL worker lock

[Ritesh Harjani (IBM)]

dtl_worker_{enable,disable}() needs annotations since they acquire and
release locks. So this adds conditional annotation based on return value.

Let's also disable context analysis for vcpudispatch_stats_write(),
since based on received input, it can leave the lock held until a later
write of 0 unlocks it. So we need to mark it with __context_unsafe().

Otherwise we get following error on enabling CONTEXT_ANALYSIS on this
file:
  lpar.c:490:9: error: rw_semaphore 'dtl_access_lock' is not held on every path through here [-Werror,-Wthread-safety-analysis]
  lpar.c:498:2: error: releasing rw_semaphore 'dtl_access_lock' that was not held [-Werror,-Wthread-safety-analysis]

Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
---
 arch/powerpc/platforms/pseries/lpar.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
index 5dbf447d3a83..9965ead1e93c 100644
--- a/arch/powerpc/platforms/pseries/lpar.c
+++ b/arch/powerpc/platforms/pseries/lpar.c
@@ -461,6 +461,7 @@ static void reset_global_dtl_mask(void)
 }
 
 static int dtl_worker_enable(unsigned long *time_limit)
+		__cond_acquires(0, &dtl_access_lock)
 {
 	int rc = 0, state;
 
@@ -491,6 +492,7 @@ static int dtl_worker_enable(unsigned long *time_limit)
 }
 
 static void dtl_worker_disable(unsigned long *time_limit)
+		__releases(&dtl_access_lock)
 {
 	cpuhp_remove_state(dtl_worker_state);
 	free_dtl_buffers(time_limit);
@@ -500,6 +502,7 @@ static void dtl_worker_disable(unsigned long *time_limit)
 
 static ssize_t vcpudispatch_stats_write(struct file *file, const char __user *p,
 		size_t count, loff_t *ppos)
+		__context_unsafe(/* dtl_access_lock is held from enable write until disable write */)
 {
 	unsigned long time_limit = jiffies + HZ;
 	struct vcpu_dispatch_data *disp;
-- 
2.39.5

[RFC 05/12] powerpc/pseries: Annotate the VPD sequence lock context

[Ritesh Harjani (IBM)]

Clang's context analysis reports:
  papr-vpd.c:151:1: error: mutex 'rtas_ibm_get_vpd_lock' is still held at the end of function [-Werror,-Wthread-safety-analysis]
  papr-vpd.c:165:2: error: releasing mutex 'rtas_ibm_get_vpd_lock' that was not held [-Werror,-Wthread-safety-analysis]

Add the necessary annotations to in vpd_sequence_{begin|end}(),
to fix these errors for enabling Clang context analysis.

Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
---
 arch/powerpc/platforms/pseries/papr-vpd.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/powerpc/platforms/pseries/papr-vpd.c b/arch/powerpc/platforms/pseries/papr-vpd.c
index f38c188fc4a1..8d210454cff1 100644
--- a/arch/powerpc/platforms/pseries/papr-vpd.c
+++ b/arch/powerpc/platforms/pseries/papr-vpd.c
@@ -123,8 +123,10 @@ static int rtas_ibm_get_vpd(struct rtas_ibm_get_vpd_params *params)
  * @seq: vpd call parameters from sequence struct
  *
  * Context: May sleep.
+ * Returns with rtas_ibm_get_vpd_lock held. vpd_sequence_end() releases it.
  */
 static void vpd_sequence_begin(struct papr_rtas_sequence *seq)
+		__acquires(&rtas_ibm_get_vpd_lock)
 {
 	struct rtas_ibm_get_vpd_params *vpd_params;
 	/*
@@ -157,6 +159,7 @@ static void vpd_sequence_begin(struct papr_rtas_sequence *seq)
  * Releases resources obtained by vpd_sequence_begin().
  */
 static void vpd_sequence_end(struct papr_rtas_sequence *seq)
+		__releases(&rtas_ibm_get_vpd_lock)
 {
 	struct rtas_ibm_get_vpd_params *vpd_params;
 
-- 
2.39.5

[RFC 06/12] powerpc/pseries: Annotate the RTAS indices sequence lock context

[Ritesh Harjani (IBM)]

Clang's context analysis reports:
  papr-indices.c:145:1: error: mutex 'rtas_ibm_get_indices_lock' is still held at the end of function [-Werror,-Wthread-safety-analysis]
  papr-indices.c:158:2: error: releasing mutex 'rtas_ibm_get_indices_lock' that was not held [-Werror,-Wthread-safety-analysis]

Add the necessary annotations to indices_sequence_{begin|end}(),
to fix these errors for enabling Clang context analysis.

Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
---
 arch/powerpc/platforms/pseries/papr-indices.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/powerpc/platforms/pseries/papr-indices.c b/arch/powerpc/platforms/pseries/papr-indices.c
index 3c7545591c45..3f3b88f708a3 100644
--- a/arch/powerpc/platforms/pseries/papr-indices.c
+++ b/arch/powerpc/platforms/pseries/papr-indices.c
@@ -126,8 +126,10 @@ static int rtas_ibm_get_indices(struct rtas_get_indices_params *params)
  * indices_sequence_begin() - Begin a indices retrieval sequence.
  *
  * Context: May sleep.
+ * Returns with rtas_ibm_get_indices_lock held. indices_sequence_end() releases it.
  */
 static void indices_sequence_begin(struct papr_rtas_sequence *seq)
+		__acquires(&rtas_ibm_get_indices_lock)
 {
 	struct rtas_get_indices_params  *param;
 
@@ -150,6 +152,7 @@ static void indices_sequence_begin(struct papr_rtas_sequence *seq)
  * Releases resources obtained by indices_sequence_begin().
  */
 static void indices_sequence_end(struct papr_rtas_sequence *seq)
+		__releases(&rtas_ibm_get_indices_lock)
 {
 	struct rtas_get_indices_params *param;
 
-- 
2.39.5

[RFC 07/12] powerpc/pseries: Annotate the RTAS physical-attestation sequence lock context

[Ritesh Harjani (IBM)]

Clang's context analysis reports:
  papr-phy-attest.c:154:1: error: mutex 'rtas_ibm_physical_attestation_lock' is still held at the end of function [-Werror,-Wthread-safety-analysis]
  papr-phy-attest.c:169:2: error: releasing mutex 'rtas_ibm_physical_attestation_lock' that was not held [-Werror,-Wthread-safety-analysis]

Add the necessary annotations to phy_attest_sequence_{begin|end}(),
to fix these errors for enabling Clang context analysis.

Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
---
 arch/powerpc/platforms/pseries/papr-phy-attest.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/powerpc/platforms/pseries/papr-phy-attest.c b/arch/powerpc/platforms/pseries/papr-phy-attest.c
index 350ba26e5962..d2bc5c0da422 100644
--- a/arch/powerpc/platforms/pseries/papr-phy-attest.c
+++ b/arch/powerpc/platforms/pseries/papr-phy-attest.c
@@ -133,8 +133,11 @@ static int rtas_physical_attestation(struct rtas_phy_attest_params *params)
  * @seq: user specified parameters for RTAS call from seq struct.
  *
  * Context: May sleep.
+ * Returns with rtas_ibm_physical_attestation_lock held.
+ * phy_attest_sequence_end() releases it.
  */
 static void phy_attest_sequence_begin(struct papr_rtas_sequence *seq)
+		__acquires(&rtas_ibm_physical_attestation_lock)
 {
 	struct rtas_phy_attest_params *param;
 
@@ -161,6 +164,7 @@ static void phy_attest_sequence_begin(struct papr_rtas_sequence *seq)
  * Releases resources obtained by phy_attest_sequence_begin().
  */
 static void phy_attest_sequence_end(struct papr_rtas_sequence *seq)
+		__releases(&rtas_ibm_physical_attestation_lock)
 {
 	struct rtas_phy_attest_params *param;
 
-- 
2.39.5

[RFC 08/12] powerpc/pseries: Annotate the DTL debugfs read lock context

[Ritesh Harjani (IBM)]

Clang's context analysis reports:
  dtl.c: error: rw_semaphore 'dtl_access_lock' is still held at the end of function [-Werror,-Wthread-safety-analysis]
  dtl.c: error: releasing rw_semaphore 'dtl_access_lock' that was not held [-Werror,-Wthread-safety-analysis]

Add the necessary annotations to phy_attest_sequence_{begin|end}(),
to fix these errors for enabling Clang context analysis.

Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
---
 arch/powerpc/platforms/pseries/dtl.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/powerpc/platforms/pseries/dtl.c b/arch/powerpc/platforms/pseries/dtl.c
index f293588b8c7b..18c597210103 100644
--- a/arch/powerpc/platforms/pseries/dtl.c
+++ b/arch/powerpc/platforms/pseries/dtl.c
@@ -177,7 +177,12 @@ static u64 dtl_current_index(struct dtl *dtl)
 }
 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
 
+/*
+ * On success the read lock stays held until dtl_disable(). That covers
+ * the whole time the debugfs file is open.
+ */
 static int dtl_enable(struct dtl *dtl)
+		__cond_acquires_shared(0, &dtl_access_lock)
 {
 	long int n_entries;
 	long int rc;
@@ -225,6 +230,7 @@ static int dtl_enable(struct dtl *dtl)
 }
 
 static void dtl_disable(struct dtl *dtl)
+		__releases_shared(&dtl_access_lock)
 {
 	spin_lock(&dtl->lock);
 	dtl_stop(dtl);
@@ -238,6 +244,7 @@ static void dtl_disable(struct dtl *dtl)
 /* file interface */
 
 static int dtl_file_open(struct inode *inode, struct file *filp)
+		__cond_acquires_shared(0, &dtl_access_lock)
 {
 	struct dtl *dtl = inode->i_private;
 	int rc;
@@ -251,6 +258,7 @@ static int dtl_file_open(struct inode *inode, struct file *filp)
 }
 
 static int dtl_file_release(struct inode *inode, struct file *filp)
+		__releases_shared(&dtl_access_lock)
 {
 	struct dtl *dtl = inode->i_private;
 	dtl_disable(dtl);
-- 
2.39.5

Re: [RFC 08/12] powerpc/pseries: Annotate the DTL debugfs read lock context

[Ritesh Harjani]

"Ritesh Harjani (IBM)" <ritesh.list@gmail.com> writes:

> Clang's context analysis reports:
>   dtl.c: error: rw_semaphore 'dtl_access_lock' is still held at the end of function [-Werror,-Wthread-safety-analysis]
>   dtl.c: error: releasing rw_semaphore 'dtl_access_lock' that was not held [-Werror,-Wthread-safety-analysis]
>
> Add the necessary annotations to phy_attest_sequence_{begin|end}(),
> to fix these errors for enabling Clang context analysis.

Sashiko pointed out:
  "Does this commit message reference the wrong functions here?"

So here is the corrected version:
 Add the necessary annotations to dtl_{enable|disable}(), dtl_file{open|release}(),
 to fix these errors for enabling Clang context analysis.

I will wait for any review comments before revising v2.

-ritesh

[RFC 09/12] powerpc/pseries: Disable context analysis for the CMM hotplug notifier

[Ritesh Harjani (IBM)]

Clang's context analysis reports:
  cmm.c: error: mutex 'hotplug_mutex' is still held at the end of function [-Werror,-Wthread-safety-analysis]
  cmm.c: error: releasing mutex 'hotplug_mutex' that was not held [-Werror,-Wthread-safety-analysis]

cmm_memory_cb() takes hotplug_mutex on MEM_GOING_OFFLINE and drops it
on a later MEM_OFFLINE or MEM_CANCEL_OFFLINE call.

Add __context_unsafe() annotation for cmm_memory_cb() callback to avoid
the reported build error in order to enable Clang context analysis.

Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
---
 arch/powerpc/platforms/pseries/cmm.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/powerpc/platforms/pseries/cmm.c b/arch/powerpc/platforms/pseries/cmm.c
index 38e22125b96f..159efe734785 100644
--- a/arch/powerpc/platforms/pseries/cmm.c
+++ b/arch/powerpc/platforms/pseries/cmm.c
@@ -470,6 +470,7 @@ static struct notifier_block cmm_reboot_nb = {
  **/
 static int cmm_memory_cb(struct notifier_block *self,
 			unsigned long action, void *arg)
+		__context_unsafe(/* Conditional locking */)
 {
 	switch (action) {
 	case MEM_GOING_OFFLINE:
-- 
2.39.5

[RFC 10/12] powerpc/pseries: Enable context analysis

[Ritesh Harjani (IBM)]

pseries objects now build with Clang context analysis enabled.
Turn it on for the directory.

This checks that each lock taken in this code is dropped on every path.

Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
---
 arch/powerpc/platforms/pseries/Makefile | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/powerpc/platforms/pseries/Makefile b/arch/powerpc/platforms/pseries/Makefile
index 3ced289a675b..d5f9beec33cc 100644
--- a/arch/powerpc/platforms/pseries/Makefile
+++ b/arch/powerpc/platforms/pseries/Makefile
@@ -1,4 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
+
+CONTEXT_ANALYSIS			:= y
+
 ccflags-$(CONFIG_PPC_PSERIES_DEBUG)	+= -DDEBUG
 
 obj-y			:= lpar.o hvCall.o nvram.o reconfig.o \
-- 
2.39.5

[RFC 11/12] powerpc/powernv: Rework OPAL console write to remove conditional locking

[Ritesh Harjani (IBM)]

Clang's context analysis reports:
  opal.c:454:7: error: spinlock 'opal_write_lock' is not held on every path through here [-Werror,-Wthread-safety-analysis]
  opal.c:493:3: error: releasing spinlock 'opal_write_lock' that was not held [-Werror,-Wthread-safety-analysis]

This patch rework the OPAL console write function to remove this
conditional locking to fix the reported build errors while enabling
Clang context analysis. We could have marked __context_unsafe(),
but this anyways simplifies the locking a bit.

Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
---
 arch/powerpc/platforms/powernv/opal.c | 30 ++++++++++++++++++---------
 1 file changed, 20 insertions(+), 10 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c
index 1946dbdc9fa1..aea83c4be76d 100644
--- a/arch/powerpc/platforms/powernv/opal.c
+++ b/arch/powerpc/platforms/powernv/opal.c
@@ -438,19 +438,13 @@ ssize_t opal_get_chars(uint32_t vtermno, u8 *buf, size_t count)
 	return 0;
 }
 
-static ssize_t __opal_put_chars(uint32_t vtermno, const u8 *data,
-				size_t total_len, bool atomic)
+static ssize_t __opal_put_chars_unlocked(uint32_t vtermno, const u8 *data,
+					 size_t total_len, bool atomic)
 {
-	unsigned long flags = 0 /* shut up gcc */;
 	ssize_t written;
 	__be64 olen;
 	s64 rc;
 
-	if (!opal.entry)
-		return -ENODEV;
-
-	if (atomic)
-		spin_lock_irqsave(&opal_write_lock, flags);
 	rc = opal_console_write_buffer_space(vtermno, &olen);
 	if (rc || be64_to_cpu(olen) < total_len) {
 		/* Closed -> drop characters */
@@ -489,10 +483,26 @@ static ssize_t __opal_put_chars(uint32_t vtermno, const u8 *data,
 	}
 
 out:
-	if (atomic)
+	return written;
+}
+
+static ssize_t __opal_put_chars(uint32_t vtermno, const u8 *data,
+				size_t total_len, bool atomic)
+{
+	unsigned long flags = 0;
+	ssize_t written;
+
+	if (!opal.entry)
+		return -ENODEV;
+
+	if (atomic) {
+		spin_lock_irqsave(&opal_write_lock, flags);
+		written = __opal_put_chars_unlocked(vtermno, data, total_len, true);
 		spin_unlock_irqrestore(&opal_write_lock, flags);
+		return written;
+	}
 
-	return written;
+	return __opal_put_chars_unlocked(vtermno, data, total_len, false);
 }
 
 ssize_t opal_put_chars(uint32_t vtermno, const u8 *data, size_t total_len)
-- 
2.39.5

[RFC 12/12] powerpc/powernv: Enable context analysis

[Ritesh Harjani (IBM)]

powernv objects now build with Clang context analysis enabled.
Turn it on for the directory.

This checks that each lock taken in this code is dropped on every path.

Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
---
 arch/powerpc/platforms/powernv/Makefile | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/powerpc/platforms/powernv/Makefile b/arch/powerpc/platforms/powernv/Makefile
index 9e5d0c847ee2..834a56122aaa 100644
--- a/arch/powerpc/platforms/powernv/Makefile
+++ b/arch/powerpc/platforms/powernv/Makefile
@@ -1,5 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 
+CONTEXT_ANALYSIS	:= y
+
 # nothing that deals with real mode is safe to KASAN
 # in particular, idle code runs a bunch of things in real mode
 KASAN_SANITIZE_idle.o := n
-- 
2.39.5