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* [PATCH net-next 0/4] net: ipa: kill IPA_VALIDATION
@ 2021-07-26 17:40 Alex Elder
  2021-07-26 17:40 ` [PATCH net-next 1/4] net: ipa: fix ipa_cmd_table_valid() Alex Elder
                   ` (5 more replies)
  0 siblings, 6 replies; 11+ messages in thread
From: Alex Elder @ 2021-07-26 17:40 UTC (permalink / raw)
  To: davem, kuba
  Cc: leon, bjorn.andersson, evgreen, cpratapa, subashab, elder,
	netdev, linux-kernel

A few months ago I proposed cleaning up some code that validates
certain things conditionally, arguing that doing so once is enough,
thus doing so always should not be necessary.
  https://lore.kernel.org/netdev/20210320141729.1956732-1-elder@linaro.org/
Leon Romanovsky felt strongly that this was a mistake, and in the
end I agreed to change my plans.

This series finally completes what I said I would do about this,
ultimately eliminating the IPA_VALIDATION symbol and conditional
code entirely.

The first patch both extends and simplifies some validation done for
IPA immediate commands, and performs those tests unconditionally.

The second patch fixes a bug that wasn't normally exposed because of
the conditional compilation (a reason Leon was right about this).
It makes filter and routing table validation occur unconditionally.

The third eliminates the remaining conditionally-defined code and
removes the line in the Makefile used to enable validation.

And the fourth removes all comments containing ipa_assert()
statements, replacing most of them with WARN_ON() calls.

					-Alex

Alex Elder (4):
  net: ipa: fix ipa_cmd_table_valid()
  net: ipa: always validate filter and route tables
  net: ipa: kill the remaining conditional validation code
  net: ipa: use WARN_ON() rather than assertions

 drivers/net/ipa/Makefile        |  3 --
 drivers/net/ipa/gsi.c           |  2 --
 drivers/net/ipa/gsi_trans.c     | 34 +++++++++++-----------
 drivers/net/ipa/ipa_cmd.c       | 51 +++++++++++++++++++--------------
 drivers/net/ipa/ipa_cmd.h       | 22 +-------------
 drivers/net/ipa/ipa_endpoint.c  | 26 ++++++++++-------
 drivers/net/ipa/ipa_interrupt.c |  8 ++++--
 drivers/net/ipa/ipa_main.c      |  7 +----
 drivers/net/ipa/ipa_reg.h       | 12 ++++----
 drivers/net/ipa/ipa_resource.c  |  3 +-
 drivers/net/ipa/ipa_table.c     | 40 ++++++++++++--------------
 drivers/net/ipa/ipa_table.h     | 16 -----------
 12 files changed, 96 insertions(+), 128 deletions(-)

-- 
2.27.0


^ permalink raw reply	[flat|nested] 11+ messages in thread

* [PATCH net-next 1/4] net: ipa: fix ipa_cmd_table_valid()
  2021-07-26 17:40 [PATCH net-next 0/4] net: ipa: kill IPA_VALIDATION Alex Elder
@ 2021-07-26 17:40 ` Alex Elder
  2021-07-26 17:40 ` [PATCH net-next 2/4] net: ipa: always validate filter and route tables Alex Elder
                   ` (4 subsequent siblings)
  5 siblings, 0 replies; 11+ messages in thread
From: Alex Elder @ 2021-07-26 17:40 UTC (permalink / raw)
  To: davem, kuba
  Cc: leon, bjorn.andersson, evgreen, cpratapa, subashab, elder,
	netdev, linux-kernel

Stop supporting different sizes for hashed and non-hashed filter or
route tables.  Add BUILD_BUG_ON() calls to verify the sizes of the
fields in the filter/route table initialization immediate command
are the same.

Add a check to ipa_cmd_table_valid() to ensure the size of the
memory region being checked fits within the immediate command field
that must hold it.

Remove two Boolean parameters used only for error reporting.  This
actually fixes a bug that would only show up if IPA_VALIDATE were
defined.  Define ipa_cmd_table_valid() unconditionally (no longer
dependent on IPA_VALIDATE).

Signed-off-by: Alex Elder <elder@linaro.org>
---
 drivers/net/ipa/ipa_cmd.c   | 38 ++++++++++++++++++++++++-------------
 drivers/net/ipa/ipa_cmd.h   | 15 +++------------
 drivers/net/ipa/ipa_table.c |  2 +-
 3 files changed, 29 insertions(+), 26 deletions(-)

diff --git a/drivers/net/ipa/ipa_cmd.c b/drivers/net/ipa/ipa_cmd.c
index af44ca41189e3..bda8677eae88d 100644
--- a/drivers/net/ipa/ipa_cmd.c
+++ b/drivers/net/ipa/ipa_cmd.c
@@ -159,35 +159,45 @@ static void ipa_cmd_validate_build(void)
 	BUILD_BUG_ON(TABLE_SIZE > field_max(IP_FLTRT_FLAGS_NHASH_SIZE_FMASK));
 #undef TABLE_COUNT_MAX
 #undef TABLE_SIZE
-}
 
-#ifdef IPA_VALIDATE
+	/* Hashed and non-hashed fields are assumed to be the same size */
+	BUILD_BUG_ON(field_max(IP_FLTRT_FLAGS_HASH_SIZE_FMASK) !=
+		     field_max(IP_FLTRT_FLAGS_NHASH_SIZE_FMASK));
+	BUILD_BUG_ON(field_max(IP_FLTRT_FLAGS_HASH_ADDR_FMASK) !=
+		     field_max(IP_FLTRT_FLAGS_NHASH_ADDR_FMASK));
+}
 
 /* Validate a memory region holding a table */
-bool ipa_cmd_table_valid(struct ipa *ipa, const struct ipa_mem *mem,
-			 bool route, bool ipv6, bool hashed)
+bool ipa_cmd_table_valid(struct ipa *ipa, const struct ipa_mem *mem, bool route)
 {
+	u32 offset_max = field_max(IP_FLTRT_FLAGS_NHASH_ADDR_FMASK);
+	u32 size_max = field_max(IP_FLTRT_FLAGS_NHASH_SIZE_FMASK);
+	const char *table = route ? "route" : "filter";
 	struct device *dev = &ipa->pdev->dev;
-	u32 offset_max;
 
-	offset_max = hashed ? field_max(IP_FLTRT_FLAGS_HASH_ADDR_FMASK)
-			    : field_max(IP_FLTRT_FLAGS_NHASH_ADDR_FMASK);
+	/* Size must fit in the immediate command field that holds it */
+	if (mem->size > size_max) {
+		dev_err(dev, "%s table region size too large\n", table);
+		dev_err(dev, "    (0x%04x > 0x%04x)\n",
+			mem->size, size_max);
+
+		return false;
+	}
+
+	/* Offset must fit in the immediate command field that holds it */
 	if (mem->offset > offset_max ||
 	    ipa->mem_offset > offset_max - mem->offset) {
-		dev_err(dev, "IPv%c %s%s table region offset too large\n",
-			ipv6 ? '6' : '4', hashed ? "hashed " : "",
-			route ? "route" : "filter");
+		dev_err(dev, "%s table region offset too large\n", table);
 		dev_err(dev, "    (0x%04x + 0x%04x > 0x%04x)\n",
 			ipa->mem_offset, mem->offset, offset_max);
 
 		return false;
 	}
 
+	/* Entire memory range must fit within IPA-local memory */
 	if (mem->offset > ipa->mem_size ||
 	    mem->size > ipa->mem_size - mem->offset) {
-		dev_err(dev, "IPv%c %s%s table region out of range\n",
-			ipv6 ? '6' : '4', hashed ? "hashed " : "",
-			route ? "route" : "filter");
+		dev_err(dev, "%s table region out of range\n", table);
 		dev_err(dev, "    (0x%04x + 0x%04x > 0x%04x)\n",
 			mem->offset, mem->size, ipa->mem_size);
 
@@ -197,6 +207,8 @@ bool ipa_cmd_table_valid(struct ipa *ipa, const struct ipa_mem *mem,
 	return true;
 }
 
+#ifdef IPA_VALIDATE
+
 /* Validate the memory region that holds headers */
 static bool ipa_cmd_header_valid(struct ipa *ipa)
 {
diff --git a/drivers/net/ipa/ipa_cmd.h b/drivers/net/ipa/ipa_cmd.h
index b99262281f41c..ea723419c826b 100644
--- a/drivers/net/ipa/ipa_cmd.h
+++ b/drivers/net/ipa/ipa_cmd.h
@@ -57,20 +57,18 @@ struct ipa_cmd_info {
 	enum dma_data_direction direction;
 };
 
-#ifdef IPA_VALIDATE
-
 /**
  * ipa_cmd_table_valid() - Validate a memory region holding a table
  * @ipa:	- IPA pointer
  * @mem:	- IPA memory region descriptor
  * @route:	- Whether the region holds a route or filter table
- * @ipv6:	- Whether the table is for IPv6 or IPv4
- * @hashed:	- Whether the table is hashed or non-hashed
  *
  * Return:	true if region is valid, false otherwise
  */
 bool ipa_cmd_table_valid(struct ipa *ipa, const struct ipa_mem *mem,
-			    bool route, bool ipv6, bool hashed);
+			    bool route);
+
+#ifdef IPA_VALIDATE
 
 /**
  * ipa_cmd_data_valid() - Validate command-realted configuration is valid
@@ -82,13 +80,6 @@ bool ipa_cmd_data_valid(struct ipa *ipa);
 
 #else /* !IPA_VALIDATE */
 
-static inline bool ipa_cmd_table_valid(struct ipa *ipa,
-				       const struct ipa_mem *mem, bool route,
-				       bool ipv6, bool hashed)
-{
-	return true;
-}
-
 static inline bool ipa_cmd_data_valid(struct ipa *ipa)
 {
 	return true;
diff --git a/drivers/net/ipa/ipa_table.c b/drivers/net/ipa/ipa_table.c
index c617a9156f26d..4f5b6749f6aae 100644
--- a/drivers/net/ipa/ipa_table.c
+++ b/drivers/net/ipa/ipa_table.c
@@ -161,7 +161,7 @@ ipa_table_valid_one(struct ipa *ipa, enum ipa_mem_id mem_id, bool route)
 	else
 		size = (1 + IPA_FILTER_COUNT_MAX) * sizeof(__le64);
 
-	if (!ipa_cmd_table_valid(ipa, mem, route, ipv6, hashed))
+	if (!ipa_cmd_table_valid(ipa, mem, route))
 		return false;
 
 	/* mem->size >= size is sufficient, but we'll demand more */
-- 
2.27.0


^ permalink raw reply	[flat|nested] 11+ messages in thread

* [PATCH net-next 2/4] net: ipa: always validate filter and route tables
  2021-07-26 17:40 [PATCH net-next 0/4] net: ipa: kill IPA_VALIDATION Alex Elder
  2021-07-26 17:40 ` [PATCH net-next 1/4] net: ipa: fix ipa_cmd_table_valid() Alex Elder
@ 2021-07-26 17:40 ` Alex Elder
  2021-07-26 17:40 ` [PATCH net-next 3/4] net: ipa: kill the remaining conditional validation code Alex Elder
                   ` (3 subsequent siblings)
  5 siblings, 0 replies; 11+ messages in thread
From: Alex Elder @ 2021-07-26 17:40 UTC (permalink / raw)
  To: davem, kuba
  Cc: leon, bjorn.andersson, evgreen, cpratapa, subashab, elder,
	netdev, linux-kernel

All checks in ipa_table_validate_build() are computed at build time,
so build that unconditionally.

In ipa_table_valid() calls to ipa_table_valid_one() are missing the
IPA pointer parameter is missing in (a bug that shows up only when
IPA_VALIDATE is defined).  Don't bother checking whether hashed
table memory regions are valid if hashed tables are not supported.

With those things fixed, have these table validation functions built
unconditionally (not dependent on IPA_VALIDATE).

Signed-off-by: Alex Elder <elder@linaro.org>
---
 drivers/net/ipa/ipa_table.c | 36 +++++++++++++++++-------------------
 drivers/net/ipa/ipa_table.h | 16 ----------------
 2 files changed, 17 insertions(+), 35 deletions(-)

diff --git a/drivers/net/ipa/ipa_table.c b/drivers/net/ipa/ipa_table.c
index 4f5b6749f6aae..c607ebec74567 100644
--- a/drivers/net/ipa/ipa_table.c
+++ b/drivers/net/ipa/ipa_table.c
@@ -120,8 +120,6 @@
  */
 #define IPA_ZERO_RULE_SIZE		(2 * sizeof(__le32))
 
-#ifdef IPA_VALIDATE
-
 /* Check things that can be validated at build time. */
 static void ipa_table_validate_build(void)
 {
@@ -169,7 +167,7 @@ ipa_table_valid_one(struct ipa *ipa, enum ipa_mem_id mem_id, bool route)
 		return true;
 
 	/* Hashed table regions can be zero size if hashing is not supported */
-	if (hashed && !mem->size)
+	if (ipa_table_hash_support(ipa) && !mem->size)
 		return true;
 
 	dev_err(dev, "%s table region %u size 0x%02x, expected 0x%02x\n",
@@ -183,14 +181,22 @@ bool ipa_table_valid(struct ipa *ipa)
 {
 	bool valid;
 
-	valid = ipa_table_valid_one(IPA_MEM_V4_FILTER, false);
-	valid = valid && ipa_table_valid_one(IPA_MEM_V4_FILTER_HASHED, false);
-	valid = valid && ipa_table_valid_one(IPA_MEM_V6_FILTER, false);
-	valid = valid && ipa_table_valid_one(IPA_MEM_V6_FILTER_HASHED, false);
-	valid = valid && ipa_table_valid_one(IPA_MEM_V4_ROUTE, true);
-	valid = valid && ipa_table_valid_one(IPA_MEM_V4_ROUTE_HASHED, true);
-	valid = valid && ipa_table_valid_one(IPA_MEM_V6_ROUTE, true);
-	valid = valid && ipa_table_valid_one(IPA_MEM_V6_ROUTE_HASHED, true);
+	valid = ipa_table_valid_one(ipa, IPA_MEM_V4_FILTER, false);
+	valid = valid && ipa_table_valid_one(ipa, IPA_MEM_V6_FILTER, false);
+	valid = valid && ipa_table_valid_one(ipa, IPA_MEM_V4_ROUTE, true);
+	valid = valid && ipa_table_valid_one(ipa, IPA_MEM_V6_ROUTE, true);
+
+	if (!ipa_table_hash_support(ipa))
+		return valid;
+
+	valid = valid && ipa_table_valid_one(ipa, IPA_MEM_V4_FILTER_HASHED,
+					     false);
+	valid = valid && ipa_table_valid_one(ipa, IPA_MEM_V6_FILTER_HASHED,
+					     false);
+	valid = valid && ipa_table_valid_one(ipa, IPA_MEM_V4_ROUTE_HASHED,
+					     true);
+	valid = valid && ipa_table_valid_one(ipa, IPA_MEM_V6_ROUTE_HASHED,
+					     true);
 
 	return valid;
 }
@@ -217,14 +223,6 @@ bool ipa_filter_map_valid(struct ipa *ipa, u32 filter_map)
 	return true;
 }
 
-#else /* !IPA_VALIDATE */
-static void ipa_table_validate_build(void)
-
-{
-}
-
-#endif /* !IPA_VALIDATE */
-
 /* Zero entry count means no table, so just return a 0 address */
 static dma_addr_t ipa_table_addr(struct ipa *ipa, bool filter_mask, u16 count)
 {
diff --git a/drivers/net/ipa/ipa_table.h b/drivers/net/ipa/ipa_table.h
index 1e2be9fce2f81..b6a9a0d79d68e 100644
--- a/drivers/net/ipa/ipa_table.h
+++ b/drivers/net/ipa/ipa_table.h
@@ -16,8 +16,6 @@ struct ipa;
 /* The maximum number of route table entries (IPv4, IPv6; hashed or not) */
 #define IPA_ROUTE_COUNT_MAX	15
 
-#ifdef IPA_VALIDATE
-
 /**
  * ipa_table_valid() - Validate route and filter table memory regions
  * @ipa:	IPA pointer
@@ -35,20 +33,6 @@ bool ipa_table_valid(struct ipa *ipa);
  */
 bool ipa_filter_map_valid(struct ipa *ipa, u32 filter_mask);
 
-#else /* !IPA_VALIDATE */
-
-static inline bool ipa_table_valid(struct ipa *ipa)
-{
-	return true;
-}
-
-static inline bool ipa_filter_map_valid(struct ipa *ipa, u32 filter_mask)
-{
-	return true;
-}
-
-#endif /* !IPA_VALIDATE */
-
 /**
  * ipa_table_hash_support() - Return true if hashed tables are supported
  * @ipa:	IPA pointer
-- 
2.27.0


^ permalink raw reply	[flat|nested] 11+ messages in thread

* [PATCH net-next 3/4] net: ipa: kill the remaining conditional validation code
  2021-07-26 17:40 [PATCH net-next 0/4] net: ipa: kill IPA_VALIDATION Alex Elder
  2021-07-26 17:40 ` [PATCH net-next 1/4] net: ipa: fix ipa_cmd_table_valid() Alex Elder
  2021-07-26 17:40 ` [PATCH net-next 2/4] net: ipa: always validate filter and route tables Alex Elder
@ 2021-07-26 17:40 ` Alex Elder
  2021-07-26 17:40 ` [PATCH net-next 4/4] net: ipa: use WARN_ON() rather than assertions Alex Elder
                   ` (2 subsequent siblings)
  5 siblings, 0 replies; 11+ messages in thread
From: Alex Elder @ 2021-07-26 17:40 UTC (permalink / raw)
  To: davem, kuba
  Cc: leon, bjorn.andersson, evgreen, cpratapa, subashab, elder,
	netdev, linux-kernel

There are only a few remaining spots that validate IPA code
conditional on whether a symbol is defined at compile time.
The checks are not expensive, so just build them always.

This completes the removal of all CONFIG_VALIDATE/CONFIG_VALIDATION
IPA code.

Signed-off-by: Alex Elder <elder@linaro.org>
---
 drivers/net/ipa/Makefile       |  3 ---
 drivers/net/ipa/gsi.c          |  2 --
 drivers/net/ipa/gsi_trans.c    |  4 ----
 drivers/net/ipa/ipa_cmd.c      |  3 ---
 drivers/net/ipa/ipa_cmd.h      | 11 -----------
 drivers/net/ipa/ipa_main.c     |  2 --
 drivers/net/ipa/ipa_resource.c |  3 +--
 7 files changed, 1 insertion(+), 27 deletions(-)

diff --git a/drivers/net/ipa/Makefile b/drivers/net/ipa/Makefile
index 506f8d5cd4eeb..75435d40b9200 100644
--- a/drivers/net/ipa/Makefile
+++ b/drivers/net/ipa/Makefile
@@ -1,6 +1,3 @@
-# Un-comment the next line if you want to validate configuration data
-#ccflags-y		+=	-DIPA_VALIDATE
-
 obj-$(CONFIG_QCOM_IPA)	+=	ipa.o
 
 ipa-y			:=	ipa_main.o ipa_clock.o ipa_reg.o ipa_mem.o \
diff --git a/drivers/net/ipa/gsi.c b/drivers/net/ipa/gsi.c
index 427c68b2ad8f3..3de67ba066a68 100644
--- a/drivers/net/ipa/gsi.c
+++ b/drivers/net/ipa/gsi.c
@@ -1964,7 +1964,6 @@ static void gsi_evt_ring_init(struct gsi *gsi)
 static bool gsi_channel_data_valid(struct gsi *gsi,
 				   const struct ipa_gsi_endpoint_data *data)
 {
-#ifdef IPA_VALIDATION
 	u32 channel_id = data->channel_id;
 	struct device *dev = gsi->dev;
 
@@ -2010,7 +2009,6 @@ static bool gsi_channel_data_valid(struct gsi *gsi,
 			channel_id, data->channel.event_count);
 		return false;
 	}
-#endif /* IPA_VALIDATION */
 
 	return true;
 }
diff --git a/drivers/net/ipa/gsi_trans.c b/drivers/net/ipa/gsi_trans.c
index 8c795a6a85986..6127370facee5 100644
--- a/drivers/net/ipa/gsi_trans.c
+++ b/drivers/net/ipa/gsi_trans.c
@@ -90,14 +90,12 @@ int gsi_trans_pool_init(struct gsi_trans_pool *pool, size_t size, u32 count,
 {
 	void *virt;
 
-#ifdef IPA_VALIDATE
 	if (!size)
 		return -EINVAL;
 	if (count < max_alloc)
 		return -EINVAL;
 	if (!max_alloc)
 		return -EINVAL;
-#endif /* IPA_VALIDATE */
 
 	/* By allocating a few extra entries in our pool (one less
 	 * than the maximum number that will be requested in a
@@ -140,14 +138,12 @@ int gsi_trans_pool_init_dma(struct device *dev, struct gsi_trans_pool *pool,
 	dma_addr_t addr;
 	void *virt;
 
-#ifdef IPA_VALIDATE
 	if (!size)
 		return -EINVAL;
 	if (count < max_alloc)
 		return -EINVAL;
 	if (!max_alloc)
 		return -EINVAL;
-#endif /* IPA_VALIDATE */
 
 	/* Don't let allocations cross a power-of-two boundary */
 	size = __roundup_pow_of_two(size);
diff --git a/drivers/net/ipa/ipa_cmd.c b/drivers/net/ipa/ipa_cmd.c
index bda8677eae88d..8900f91509fee 100644
--- a/drivers/net/ipa/ipa_cmd.c
+++ b/drivers/net/ipa/ipa_cmd.c
@@ -207,8 +207,6 @@ bool ipa_cmd_table_valid(struct ipa *ipa, const struct ipa_mem *mem, bool route)
 	return true;
 }
 
-#ifdef IPA_VALIDATE
-
 /* Validate the memory region that holds headers */
 static bool ipa_cmd_header_valid(struct ipa *ipa)
 {
@@ -343,7 +341,6 @@ bool ipa_cmd_data_valid(struct ipa *ipa)
 	return true;
 }
 
-#endif /* IPA_VALIDATE */
 
 int ipa_cmd_pool_init(struct gsi_channel *channel, u32 tre_max)
 {
diff --git a/drivers/net/ipa/ipa_cmd.h b/drivers/net/ipa/ipa_cmd.h
index ea723419c826b..69cd085d427db 100644
--- a/drivers/net/ipa/ipa_cmd.h
+++ b/drivers/net/ipa/ipa_cmd.h
@@ -68,8 +68,6 @@ struct ipa_cmd_info {
 bool ipa_cmd_table_valid(struct ipa *ipa, const struct ipa_mem *mem,
 			    bool route);
 
-#ifdef IPA_VALIDATE
-
 /**
  * ipa_cmd_data_valid() - Validate command-realted configuration is valid
  * @ipa:	- IPA pointer
@@ -78,15 +76,6 @@ bool ipa_cmd_table_valid(struct ipa *ipa, const struct ipa_mem *mem,
  */
 bool ipa_cmd_data_valid(struct ipa *ipa);
 
-#else /* !IPA_VALIDATE */
-
-static inline bool ipa_cmd_data_valid(struct ipa *ipa)
-{
-	return true;
-}
-
-#endif /* !IPA_VALIDATE */
-
 /**
  * ipa_cmd_pool_init() - initialize command channel pools
  * @channel:	AP->IPA command TX GSI channel pointer
diff --git a/drivers/net/ipa/ipa_main.c b/drivers/net/ipa/ipa_main.c
index 9810c61a03202..ff5f3fab640d6 100644
--- a/drivers/net/ipa/ipa_main.c
+++ b/drivers/net/ipa/ipa_main.c
@@ -612,7 +612,6 @@ MODULE_DEVICE_TABLE(of, ipa_match);
  * */
 static void ipa_validate_build(void)
 {
-#ifdef IPA_VALIDATE
 	/* At one time we assumed a 64-bit build, allowing some do_div()
 	 * calls to be replaced by simple division or modulo operations.
 	 * We currently only perform divide and modulo operations on u32,
@@ -646,7 +645,6 @@ static void ipa_validate_build(void)
 	BUILD_BUG_ON(!ipa_aggr_granularity_val(IPA_AGGR_GRANULARITY));
 	BUILD_BUG_ON(ipa_aggr_granularity_val(IPA_AGGR_GRANULARITY) >
 			field_max(AGGR_GRANULARITY_FMASK));
-#endif /* IPA_VALIDATE */
 }
 
 static bool ipa_version_valid(enum ipa_version version)
diff --git a/drivers/net/ipa/ipa_resource.c b/drivers/net/ipa/ipa_resource.c
index 3b2dc216d3a68..e3da95d694099 100644
--- a/drivers/net/ipa/ipa_resource.c
+++ b/drivers/net/ipa/ipa_resource.c
@@ -29,7 +29,6 @@
 static bool ipa_resource_limits_valid(struct ipa *ipa,
 				      const struct ipa_resource_data *data)
 {
-#ifdef IPA_VALIDATION
 	u32 group_count;
 	u32 i;
 	u32 j;
@@ -65,7 +64,7 @@ static bool ipa_resource_limits_valid(struct ipa *ipa,
 			if (resource->limits[j].min || resource->limits[j].max)
 				return false;
 	}
-#endif /* !IPA_VALIDATION */
+
 	return true;
 }
 
-- 
2.27.0


^ permalink raw reply	[flat|nested] 11+ messages in thread

* [PATCH net-next 4/4] net: ipa: use WARN_ON() rather than assertions
  2021-07-26 17:40 [PATCH net-next 0/4] net: ipa: kill IPA_VALIDATION Alex Elder
                   ` (2 preceding siblings ...)
  2021-07-26 17:40 ` [PATCH net-next 3/4] net: ipa: kill the remaining conditional validation code Alex Elder
@ 2021-07-26 17:40 ` Alex Elder
  2021-07-26 21:52 ` [PATCH net-next 0/4] net: ipa: kill IPA_VALIDATION patchwork-bot+netdevbpf
  2021-07-27 11:16 ` Leon Romanovsky
  5 siblings, 0 replies; 11+ messages in thread
From: Alex Elder @ 2021-07-26 17:40 UTC (permalink / raw)
  To: davem, kuba
  Cc: leon, bjorn.andersson, evgreen, cpratapa, subashab, elder,
	netdev, linux-kernel

I've added commented assertions to record certain properties that
can be assumed to hold in certain places in the IPA code.  Convert
these into real WARN_ON() calls so the assertions are actually
checked, using the standard WARN_ON() mechanism.

Where errors can be returned, return an error if a warning is
triggered.

Signed-off-by: Alex Elder <elder@linaro.org>
---
 drivers/net/ipa/gsi_trans.c     | 30 ++++++++++++++++++------------
 drivers/net/ipa/ipa_cmd.c       | 14 +++++++-------
 drivers/net/ipa/ipa_endpoint.c  | 26 +++++++++++++++-----------
 drivers/net/ipa/ipa_interrupt.c |  8 +++++---
 drivers/net/ipa/ipa_main.c      |  5 +----
 drivers/net/ipa/ipa_reg.h       | 12 ++++++------
 drivers/net/ipa/ipa_table.c     |  2 +-
 7 files changed, 53 insertions(+), 44 deletions(-)

diff --git a/drivers/net/ipa/gsi_trans.c b/drivers/net/ipa/gsi_trans.c
index 6127370facee5..1544564bc2835 100644
--- a/drivers/net/ipa/gsi_trans.c
+++ b/drivers/net/ipa/gsi_trans.c
@@ -184,8 +184,8 @@ static u32 gsi_trans_pool_alloc_common(struct gsi_trans_pool *pool, u32 count)
 {
 	u32 offset;
 
-	/* assert(count > 0); */
-	/* assert(count <= pool->max_alloc); */
+	WARN_ON(!count);
+	WARN_ON(count > pool->max_alloc);
 
 	/* Allocate from beginning if wrap would occur */
 	if (count > pool->count - pool->free)
@@ -221,9 +221,10 @@ void *gsi_trans_pool_next(struct gsi_trans_pool *pool, void *element)
 {
 	void *end = pool->base + pool->count * pool->size;
 
-	/* assert(element >= pool->base); */
-	/* assert(element < end); */
-	/* assert(pool->max_alloc == 1); */
+	WARN_ON(element < pool->base);
+	WARN_ON(element >= end);
+	WARN_ON(pool->max_alloc != 1);
+
 	element += pool->size;
 
 	return element < end ? element : pool->base;
@@ -328,7 +329,8 @@ struct gsi_trans *gsi_channel_trans_alloc(struct gsi *gsi, u32 channel_id,
 	struct gsi_trans_info *trans_info;
 	struct gsi_trans *trans;
 
-	/* assert(tre_count <= gsi_channel_trans_tre_max(gsi, channel_id)); */
+	if (WARN_ON(tre_count > gsi_channel_trans_tre_max(gsi, channel_id)))
+		return NULL;
 
 	trans_info = &channel->trans_info;
 
@@ -404,7 +406,7 @@ void gsi_trans_cmd_add(struct gsi_trans *trans, void *buf, u32 size,
 	u32 which = trans->used++;
 	struct scatterlist *sg;
 
-	/* assert(which < trans->tre_count); */
+	WARN_ON(which >= trans->tre_count);
 
 	/* Commands are quite different from data transfer requests.
 	 * Their payloads come from a pool whose memory is allocated
@@ -437,8 +439,10 @@ int gsi_trans_page_add(struct gsi_trans *trans, struct page *page, u32 size,
 	struct scatterlist *sg = &trans->sgl[0];
 	int ret;
 
-	/* assert(trans->tre_count == 1); */
-	/* assert(!trans->used); */
+	if (WARN_ON(trans->tre_count != 1))
+		return -EINVAL;
+	if (WARN_ON(trans->used))
+		return -EINVAL;
 
 	sg_set_page(sg, page, size, offset);
 	ret = dma_map_sg(trans->gsi->dev, sg, 1, trans->direction);
@@ -457,8 +461,10 @@ int gsi_trans_skb_add(struct gsi_trans *trans, struct sk_buff *skb)
 	u32 used;
 	int ret;
 
-	/* assert(trans->tre_count == 1); */
-	/* assert(!trans->used); */
+	if (WARN_ON(trans->tre_count != 1))
+		return -EINVAL;
+	if (WARN_ON(trans->used))
+		return -EINVAL;
 
 	/* skb->len will not be 0 (checked early) */
 	ret = skb_to_sgvec(skb, sg, 0, skb->len);
@@ -546,7 +552,7 @@ static void __gsi_trans_commit(struct gsi_trans *trans, bool ring_db)
 	u32 avail;
 	u32 i;
 
-	/* assert(trans->used > 0); */
+	WARN_ON(!trans->used);
 
 	/* Consume the entries.  If we cross the end of the ring while
 	 * filling them we'll switch to the beginning to finish.
diff --git a/drivers/net/ipa/ipa_cmd.c b/drivers/net/ipa/ipa_cmd.c
index 8900f91509fee..cff51731195aa 100644
--- a/drivers/net/ipa/ipa_cmd.c
+++ b/drivers/net/ipa/ipa_cmd.c
@@ -165,6 +165,10 @@ static void ipa_cmd_validate_build(void)
 		     field_max(IP_FLTRT_FLAGS_NHASH_SIZE_FMASK));
 	BUILD_BUG_ON(field_max(IP_FLTRT_FLAGS_HASH_ADDR_FMASK) !=
 		     field_max(IP_FLTRT_FLAGS_NHASH_ADDR_FMASK));
+
+	/* Valid endpoint numbers must fit in the IP packet init command */
+	BUILD_BUG_ON(field_max(IPA_PACKET_INIT_DEST_ENDPOINT_FMASK) <
+		     IPA_ENDPOINT_MAX - 1);
 }
 
 /* Validate a memory region holding a table */
@@ -531,9 +535,6 @@ static void ipa_cmd_ip_packet_init_add(struct gsi_trans *trans, u8 endpoint_id)
 	union ipa_cmd_payload *cmd_payload;
 	dma_addr_t payload_addr;
 
-	/* assert(endpoint_id <
-		  field_max(IPA_PACKET_INIT_DEST_ENDPOINT_FMASK)); */
-
 	cmd_payload = ipa_cmd_payload_alloc(ipa, &payload_addr);
 	payload = &cmd_payload->ip_packet_init;
 
@@ -557,8 +558,9 @@ void ipa_cmd_dma_shared_mem_add(struct gsi_trans *trans, u32 offset, u16 size,
 	u16 flags;
 
 	/* size and offset must fit in 16 bit fields */
-	/* assert(size > 0 && size <= U16_MAX); */
-	/* assert(offset <= U16_MAX && ipa->mem_offset <= U16_MAX - offset); */
+	WARN_ON(!size);
+	WARN_ON(size > U16_MAX);
+	WARN_ON(offset > U16_MAX || ipa->mem_offset > U16_MAX - offset);
 
 	offset += ipa->mem_offset;
 
@@ -597,8 +599,6 @@ static void ipa_cmd_ip_tag_status_add(struct gsi_trans *trans)
 	union ipa_cmd_payload *cmd_payload;
 	dma_addr_t payload_addr;
 
-	/* assert(tag <= field_max(IP_PACKET_TAG_STATUS_TAG_FMASK)); */
-
 	cmd_payload = ipa_cmd_payload_alloc(ipa, &payload_addr);
 	payload = &cmd_payload->ip_packet_tag_status;
 
diff --git a/drivers/net/ipa/ipa_endpoint.c b/drivers/net/ipa/ipa_endpoint.c
index ab02669bae4e6..8070d1a1d5dfd 100644
--- a/drivers/net/ipa/ipa_endpoint.c
+++ b/drivers/net/ipa/ipa_endpoint.c
@@ -250,17 +250,18 @@ ipa_endpoint_init_ctrl(struct ipa_endpoint *endpoint, bool suspend_delay)
 
 	/* Suspend is not supported for IPA v4.0+.  Delay doesn't work
 	 * correctly on IPA v4.2.
-	 *
-	 * if (endpoint->toward_ipa)
-	 * 	assert(ipa->version != IPA_VERSION_4.2);
-	 * else
-	 *	assert(ipa->version < IPA_VERSION_4_0);
 	 */
+	if (endpoint->toward_ipa)
+		WARN_ON(ipa->version == IPA_VERSION_4_2);
+	else
+		WARN_ON(ipa->version >= IPA_VERSION_4_0);
+
 	mask = endpoint->toward_ipa ? ENDP_DELAY_FMASK : ENDP_SUSPEND_FMASK;
 
 	val = ioread32(ipa->reg_virt + offset);
-	/* Don't bother if it's already in the requested state */
 	state = !!(val & mask);
+
+	/* Don't bother if it's already in the requested state */
 	if (suspend_delay != state) {
 		val ^= mask;
 		iowrite32(val, ipa->reg_virt + offset);
@@ -273,7 +274,7 @@ ipa_endpoint_init_ctrl(struct ipa_endpoint *endpoint, bool suspend_delay)
 static void
 ipa_endpoint_program_delay(struct ipa_endpoint *endpoint, bool enable)
 {
-	/* assert(endpoint->toward_ipa); */
+	WARN_ON(!endpoint->toward_ipa);
 
 	/* Delay mode doesn't work properly for IPA v4.2 */
 	if (endpoint->ipa->version != IPA_VERSION_4_2)
@@ -287,7 +288,8 @@ static bool ipa_endpoint_aggr_active(struct ipa_endpoint *endpoint)
 	u32 offset;
 	u32 val;
 
-	/* assert(mask & ipa->available); */
+	WARN_ON(!(mask & ipa->available));
+
 	offset = ipa_reg_state_aggr_active_offset(ipa->version);
 	val = ioread32(ipa->reg_virt + offset);
 
@@ -299,7 +301,8 @@ static void ipa_endpoint_force_close(struct ipa_endpoint *endpoint)
 	u32 mask = BIT(endpoint->endpoint_id);
 	struct ipa *ipa = endpoint->ipa;
 
-	/* assert(mask & ipa->available); */
+	WARN_ON(!(mask & ipa->available));
+
 	iowrite32(mask, ipa->reg_virt + IPA_REG_AGGR_FORCE_CLOSE_OFFSET);
 }
 
@@ -338,7 +341,7 @@ ipa_endpoint_program_suspend(struct ipa_endpoint *endpoint, bool enable)
 	if (endpoint->ipa->version >= IPA_VERSION_4_0)
 		return enable;	/* For IPA v4.0+, no change made */
 
-	/* assert(!endpoint->toward_ipa); */
+	WARN_ON(endpoint->toward_ipa);
 
 	suspended = ipa_endpoint_init_ctrl(endpoint, enable);
 
@@ -1156,7 +1159,8 @@ static bool ipa_endpoint_skb_build(struct ipa_endpoint *endpoint,
 	if (!endpoint->netdev)
 		return false;
 
-	/* assert(len <= SKB_WITH_OVERHEAD(IPA_RX_BUFFER_SIZE-NET_SKB_PAD)); */
+	WARN_ON(len > SKB_WITH_OVERHEAD(IPA_RX_BUFFER_SIZE - NET_SKB_PAD));
+
 	skb = build_skb(page_address(page), IPA_RX_BUFFER_SIZE);
 	if (skb) {
 		/* Reserve the headroom and account for the data */
diff --git a/drivers/net/ipa/ipa_interrupt.c b/drivers/net/ipa/ipa_interrupt.c
index c46df0b7c4e50..e792bc3be5766 100644
--- a/drivers/net/ipa/ipa_interrupt.c
+++ b/drivers/net/ipa/ipa_interrupt.c
@@ -146,7 +146,7 @@ static void ipa_interrupt_suspend_control(struct ipa_interrupt *interrupt,
 	u32 offset;
 	u32 val;
 
-	/* assert(mask & ipa->available); */
+	WARN_ON(!(mask & ipa->available));
 
 	/* IPA version 3.0 does not support TX_SUSPEND interrupt control */
 	if (ipa->version == IPA_VERSION_3_0)
@@ -206,7 +206,8 @@ void ipa_interrupt_add(struct ipa_interrupt *interrupt,
 	struct ipa *ipa = interrupt->ipa;
 	u32 offset;
 
-	/* assert(ipa_irq < IPA_IRQ_COUNT); */
+	WARN_ON(ipa_irq >= IPA_IRQ_COUNT);
+
 	interrupt->handler[ipa_irq] = handler;
 
 	/* Update the IPA interrupt mask to enable it */
@@ -222,7 +223,8 @@ ipa_interrupt_remove(struct ipa_interrupt *interrupt, enum ipa_irq_id ipa_irq)
 	struct ipa *ipa = interrupt->ipa;
 	u32 offset;
 
-	/* assert(ipa_irq < IPA_IRQ_COUNT); */
+	WARN_ON(ipa_irq >= IPA_IRQ_COUNT);
+
 	/* Update the IPA interrupt mask to disable it */
 	interrupt->enabled &= ~BIT(ipa_irq);
 	offset = ipa_reg_irq_en_offset(ipa->version);
diff --git a/drivers/net/ipa/ipa_main.c b/drivers/net/ipa/ipa_main.c
index ff5f3fab640d6..0567d726c5608 100644
--- a/drivers/net/ipa/ipa_main.c
+++ b/drivers/net/ipa/ipa_main.c
@@ -253,9 +253,6 @@ ipa_hardware_config_qsb(struct ipa *ipa, const struct ipa_data *data)
 	const struct ipa_qsb_data *data1;
 	u32 val;
 
-	/* assert(data->qsb_count > 0); */
-	/* assert(data->qsb_count < 3); */
-
 	/* QMB 0 represents DDR; QMB 1 (if present) represents PCIe */
 	data0 = &data->qsb_data[IPA_QSB_MASTER_DDR];
 	if (data->qsb_count > 1)
@@ -293,7 +290,7 @@ ipa_hardware_config_qsb(struct ipa *ipa, const struct ipa_data *data)
  */
 static u32 ipa_aggr_granularity_val(u32 usec)
 {
-	/* assert(usec != 0); */
+	WARN_ON(!usec);
 
 	return DIV_ROUND_CLOSEST(usec * TIMER_FREQUENCY, USEC_PER_SEC) - 1;
 }
diff --git a/drivers/net/ipa/ipa_reg.h b/drivers/net/ipa/ipa_reg.h
index b89dec5865a5b..a5b355384d4ae 100644
--- a/drivers/net/ipa/ipa_reg.h
+++ b/drivers/net/ipa/ipa_reg.h
@@ -99,7 +99,7 @@ struct ipa;
 static inline u32 arbitration_lock_disable_encoded(enum ipa_version version,
 						   u32 mask)
 {
-	/* assert(version >= IPA_VERSION_4_0); */
+	WARN_ON(version < IPA_VERSION_4_0);
 
 	if (version < IPA_VERSION_4_9)
 		return u32_encode_bits(mask, GENMASK(20, 17));
@@ -116,7 +116,7 @@ static inline u32 full_flush_rsc_closure_en_encoded(enum ipa_version version,
 {
 	u32 val = enable ? 1 : 0;
 
-	/* assert(version >= IPA_VERSION_4_5); */
+	WARN_ON(version < IPA_VERSION_4_5);
 
 	if (version == IPA_VERSION_4_5 || version == IPA_VERSION_4_7)
 		return u32_encode_bits(val, GENMASK(21, 21));
@@ -409,7 +409,7 @@ static inline u32 ipa_header_size_encoded(enum ipa_version version,
 
 	val = u32_encode_bits(size, HDR_LEN_FMASK);
 	if (version < IPA_VERSION_4_5) {
-		/* ipa_assert(header_size == size); */
+		WARN_ON(header_size != size);
 		return val;
 	}
 
@@ -429,7 +429,7 @@ static inline u32 ipa_metadata_offset_encoded(enum ipa_version version,
 
 	val = u32_encode_bits(off, HDR_OFST_METADATA_FMASK);
 	if (version < IPA_VERSION_4_5) {
-		/* ipa_assert(offset == off); */
+		WARN_ON(offset != off);
 		return val;
 	}
 
@@ -812,7 +812,7 @@ ipa_reg_irq_suspend_info_offset(enum ipa_version version)
 static inline u32
 ipa_reg_irq_suspend_en_ee_n_offset(enum ipa_version version, u32 ee)
 {
-	/* assert(version != IPA_VERSION_3_0); */
+	WARN_ON(version == IPA_VERSION_3_0);
 
 	if (version < IPA_VERSION_4_9)
 		return 0x00003034 + 0x1000 * ee;
@@ -830,7 +830,7 @@ ipa_reg_irq_suspend_en_offset(enum ipa_version version)
 static inline u32
 ipa_reg_irq_suspend_clr_ee_n_offset(enum ipa_version version, u32 ee)
 {
-	/* assert(version != IPA_VERSION_3_0); */
+	WARN_ON(version == IPA_VERSION_3_0);
 
 	if (version < IPA_VERSION_4_9)
 		return 0x00003038 + 0x1000 * ee;
diff --git a/drivers/net/ipa/ipa_table.c b/drivers/net/ipa/ipa_table.c
index c607ebec74567..2324e1b93e37d 100644
--- a/drivers/net/ipa/ipa_table.c
+++ b/drivers/net/ipa/ipa_table.c
@@ -231,7 +231,7 @@ static dma_addr_t ipa_table_addr(struct ipa *ipa, bool filter_mask, u16 count)
 	if (!count)
 		return 0;
 
-/* assert(count <= max_t(u32, IPA_FILTER_COUNT_MAX, IPA_ROUTE_COUNT_MAX)); */
+	WARN_ON(count > max_t(u32, IPA_FILTER_COUNT_MAX, IPA_ROUTE_COUNT_MAX));
 
 	/* Skip over the zero rule and possibly the filter mask */
 	skip = filter_mask ? 1 : 2;
-- 
2.27.0


^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH net-next 0/4] net: ipa: kill IPA_VALIDATION
  2021-07-26 17:40 [PATCH net-next 0/4] net: ipa: kill IPA_VALIDATION Alex Elder
                   ` (3 preceding siblings ...)
  2021-07-26 17:40 ` [PATCH net-next 4/4] net: ipa: use WARN_ON() rather than assertions Alex Elder
@ 2021-07-26 21:52 ` patchwork-bot+netdevbpf
  2021-07-27 11:16 ` Leon Romanovsky
  5 siblings, 0 replies; 11+ messages in thread
From: patchwork-bot+netdevbpf @ 2021-07-26 21:52 UTC (permalink / raw)
  To: Alex Elder
  Cc: davem, kuba, leon, bjorn.andersson, evgreen, cpratapa, subashab,
	elder, netdev, linux-kernel

Hello:

This series was applied to netdev/net-next.git (refs/heads/master):

On Mon, 26 Jul 2021 12:40:06 -0500 you wrote:
> A few months ago I proposed cleaning up some code that validates
> certain things conditionally, arguing that doing so once is enough,
> thus doing so always should not be necessary.
>   https://lore.kernel.org/netdev/20210320141729.1956732-1-elder@linaro.org/
> Leon Romanovsky felt strongly that this was a mistake, and in the
> end I agreed to change my plans.
> 
> [...]

Here is the summary with links:
  - [net-next,1/4] net: ipa: fix ipa_cmd_table_valid()
    https://git.kernel.org/netdev/net-next/c/f2c1dac0abcf
  - [net-next,2/4] net: ipa: always validate filter and route tables
    https://git.kernel.org/netdev/net-next/c/546948bf3625
  - [net-next,3/4] net: ipa: kill the remaining conditional validation code
    https://git.kernel.org/netdev/net-next/c/442d68ebf092
  - [net-next,4/4] net: ipa: use WARN_ON() rather than assertions
    https://git.kernel.org/netdev/net-next/c/5bc5588466a1

You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html



^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH net-next 0/4] net: ipa: kill IPA_VALIDATION
  2021-07-26 17:40 [PATCH net-next 0/4] net: ipa: kill IPA_VALIDATION Alex Elder
                   ` (4 preceding siblings ...)
  2021-07-26 21:52 ` [PATCH net-next 0/4] net: ipa: kill IPA_VALIDATION patchwork-bot+netdevbpf
@ 2021-07-27 11:16 ` Leon Romanovsky
  2021-07-27 12:34   ` Alex Elder
  5 siblings, 1 reply; 11+ messages in thread
From: Leon Romanovsky @ 2021-07-27 11:16 UTC (permalink / raw)
  To: Alex Elder
  Cc: davem, kuba, bjorn.andersson, evgreen, cpratapa, subashab, elder,
	netdev, linux-kernel

On Mon, Jul 26, 2021 at 12:40:06PM -0500, Alex Elder wrote:
> A few months ago I proposed cleaning up some code that validates
> certain things conditionally, arguing that doing so once is enough,
> thus doing so always should not be necessary.
>   https://lore.kernel.org/netdev/20210320141729.1956732-1-elder@linaro.org/
> Leon Romanovsky felt strongly that this was a mistake, and in the
> end I agreed to change my plans.

<...>

> The second patch fixes a bug that wasn't normally exposed because of
> the conditional compilation (a reason Leon was right about this).

Thanks Alex,

If you want another anti pattern that is very popular in netdev, the following pattern is
wrong by definition :):
if (WARN_ON(...))
  return ...

The WARN_*() macros are intended catch impossible flows, something that
shouldn't exist. The idea that printed stack to dmesg and return to the
caller will fix the situation is a very naive one. That stack already
says that something very wrong in the system.

If such flow can be valid use "if(...) return ..", if not use plain
WARN_ON(...).

Thanks

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH net-next 0/4] net: ipa: kill IPA_VALIDATION
  2021-07-27 11:16 ` Leon Romanovsky
@ 2021-07-27 12:34   ` Alex Elder
  2021-07-27 12:56     ` Leon Romanovsky
  0 siblings, 1 reply; 11+ messages in thread
From: Alex Elder @ 2021-07-27 12:34 UTC (permalink / raw)
  To: Leon Romanovsky
  Cc: davem, kuba, bjorn.andersson, evgreen, cpratapa, subashab, elder,
	netdev, linux-kernel

On 7/27/21 6:16 AM, Leon Romanovsky wrote:
> On Mon, Jul 26, 2021 at 12:40:06PM -0500, Alex Elder wrote:
>> A few months ago I proposed cleaning up some code that validates
>> certain things conditionally, arguing that doing so once is enough,
>> thus doing so always should not be necessary.
>>   https://lore.kernel.org/netdev/20210320141729.1956732-1-elder@linaro.org/
>> Leon Romanovsky felt strongly that this was a mistake, and in the
>> end I agreed to change my plans.
> 
> <...>
> 
>> The second patch fixes a bug that wasn't normally exposed because of
>> the conditional compilation (a reason Leon was right about this).
> 
> Thanks Alex,
> 
> If you want another anti pattern that is very popular in netdev, the following pattern is
> wrong by definition :):
> if (WARN_ON(...))
>   return ...

I understand this reasoning.

I had it return an error if the WARN_ON() condition was true in cases
where the function returned a value and callers already handled errors.
I looked back at the patch and here is one of those cases:

gsi_channel_trans_alloc()
- If too many TREs are requested we do not want to allocate them
  from the pool, or it will cause further breakage.  By returning
  early, no transaction will be filled or committed, and an error
  message will (often) be reported, which will indicate the source
  of the error.  If any error occurs during initialization, we fail
  that whole process and everything should be cleaned up.  So in
  this case at least, returning if this ever occurred is better
  than allowing control to continue into the function.

In any case I take your point.  I will now add to my task list
a review of these spots.  I'd like to be sure an error message
*is* reported at an appropriate level up the chain of callers so
I can always identify the culprit in the a WARN_ON() fires (even
though it should never
 happen).  And in each case I'll evaluate
whether returning is better than not.

Thanks.

					-Alex

> The WARN_*() macros are intended catch impossible flows, something that
> shouldn't exist. The idea that printed stack to dmesg and return to the
> caller will fix the situation is a very naive one. That stack already
> says that something very wrong in the system.
> 
> If such flow can be valid use "if(...) return ..", if not use plain
> WARN_ON(...).
> 
> Thanks
> 


^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH net-next 0/4] net: ipa: kill IPA_VALIDATION
  2021-07-27 12:34   ` Alex Elder
@ 2021-07-27 12:56     ` Leon Romanovsky
  2021-07-27 13:40       ` Alex Elder
  0 siblings, 1 reply; 11+ messages in thread
From: Leon Romanovsky @ 2021-07-27 12:56 UTC (permalink / raw)
  To: Alex Elder
  Cc: davem, kuba, bjorn.andersson, evgreen, cpratapa, subashab, elder,
	netdev, linux-kernel

On Tue, Jul 27, 2021 at 07:34:41AM -0500, Alex Elder wrote:
> On 7/27/21 6:16 AM, Leon Romanovsky wrote:
> > On Mon, Jul 26, 2021 at 12:40:06PM -0500, Alex Elder wrote:
> >> A few months ago I proposed cleaning up some code that validates
> >> certain things conditionally, arguing that doing so once is enough,
> >> thus doing so always should not be necessary.
> >>   https://lore.kernel.org/netdev/20210320141729.1956732-1-elder@linaro.org/
> >> Leon Romanovsky felt strongly that this was a mistake, and in the
> >> end I agreed to change my plans.
> > 
> > <...>
> > 
> >> The second patch fixes a bug that wasn't normally exposed because of
> >> the conditional compilation (a reason Leon was right about this).
> > 
> > Thanks Alex,
> > 
> > If you want another anti pattern that is very popular in netdev, the following pattern is
> > wrong by definition :):
> > if (WARN_ON(...))
> >   return ...
> 
> I understand this reasoning.
> 
> I had it return an error if the WARN_ON() condition was true in cases
> where the function returned a value and callers already handled errors.
> I looked back at the patch and here is one of those cases:
> 
> gsi_channel_trans_alloc()
> - If too many TREs are requested we do not want to allocate them
>   from the pool, or it will cause further breakage.  By returning
>   early, no transaction will be filled or committed, and an error
>   message will (often) be reported, which will indicate the source
>   of the error.  If any error occurs during initialization, we fail
>   that whole process and everything should be cleaned up.  So in
>   this case at least, returning if this ever occurred is better
>   than allowing control to continue into the function.
> 
> In any case I take your point.  I will now add to my task list
> a review of these spots.  I'd like to be sure an error message
> *is* reported at an appropriate level up the chain of callers so
> I can always identify the culprit in the a WARN_ON() fires (even
> though it should never
>  happen).  And in each case I'll evaluate
> whether returning is better than not.

You can, but users don't :). So if it is valid but error flow, that
needs user awareness, simply print something to the dmesg with *_err()
prints.


BTW, I'm trying to untangle some of the flows in net/core/devlink.c
and such if(WARN()) pattern is even harmful, because it is very hard to
understand when that error is rare/non-exist/real.

Thanks

> 
> Thanks.
> 
> 					-Alex
> 
> > The WARN_*() macros are intended catch impossible flows, something that
> > shouldn't exist. The idea that printed stack to dmesg and return to the
> > caller will fix the situation is a very naive one. That stack already
> > says that something very wrong in the system.
> > 
> > If such flow can be valid use "if(...) return ..", if not use plain
> > WARN_ON(...).
> > 
> > Thanks
> > 
> 

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH net-next 0/4] net: ipa: kill IPA_VALIDATION
  2021-07-27 12:56     ` Leon Romanovsky
@ 2021-07-27 13:40       ` Alex Elder
  2021-07-27 14:03         ` Leon Romanovsky
  0 siblings, 1 reply; 11+ messages in thread
From: Alex Elder @ 2021-07-27 13:40 UTC (permalink / raw)
  To: Leon Romanovsky
  Cc: davem, kuba, bjorn.andersson, evgreen, cpratapa, subashab, elder,
	netdev, linux-kernel

On 7/27/21 7:56 AM, Leon Romanovsky wrote:
>> In any case I take your point.  I will now add to my task list
>> a review of these spots.  I'd like to be sure an error message
>> *is*  reported at an appropriate level up the chain of callers so
>> I can always identify the culprit in the a WARN_ON() fires (even
>> though it should never
>>   happen).  And in each case I'll evaluate
>> whether returning is better than not.
> You can, but users don't :). So if it is valid but error flow, that
> needs user awareness, simply print something to the dmesg with *_err()
> prints.

For some reason you seem to care about users.

I guess the WARN stack trace tells me where it comes from.
This would be an invalid error flow, and should never happen.

I'll still plan to review each of these again.

> BTW, I'm trying to untangle some of the flows in net/core/devlink.c
> and such if(WARN()) pattern is even harmful, because it is very hard to
> understand when that error is rare/non-exist/real.

That's what assert() is for, but we've already had that
discussion :)

					-Alex

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH net-next 0/4] net: ipa: kill IPA_VALIDATION
  2021-07-27 13:40       ` Alex Elder
@ 2021-07-27 14:03         ` Leon Romanovsky
  0 siblings, 0 replies; 11+ messages in thread
From: Leon Romanovsky @ 2021-07-27 14:03 UTC (permalink / raw)
  To: Alex Elder
  Cc: davem, kuba, bjorn.andersson, evgreen, cpratapa, subashab, elder,
	netdev, linux-kernel

On Tue, Jul 27, 2021 at 08:40:42AM -0500, Alex Elder wrote:
> On 7/27/21 7:56 AM, Leon Romanovsky wrote:
> > > In any case I take your point.  I will now add to my task list
> > > a review of these spots.  I'd like to be sure an error message
> > > *is*  reported at an appropriate level up the chain of callers so
> > > I can always identify the culprit in the a WARN_ON() fires (even
> > > though it should never
> > >   happen).  And in each case I'll evaluate
> > > whether returning is better than not.
> > You can, but users don't :). So if it is valid but error flow, that
> > needs user awareness, simply print something to the dmesg with *_err()
> > prints.
> 
> For some reason you seem to care about users.

Yeah, this is my Achilles heel :)

Thanks

^ permalink raw reply	[flat|nested] 11+ messages in thread

end of thread, other threads:[~2021-07-27 14:04 UTC | newest]

Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-07-26 17:40 [PATCH net-next 0/4] net: ipa: kill IPA_VALIDATION Alex Elder
2021-07-26 17:40 ` [PATCH net-next 1/4] net: ipa: fix ipa_cmd_table_valid() Alex Elder
2021-07-26 17:40 ` [PATCH net-next 2/4] net: ipa: always validate filter and route tables Alex Elder
2021-07-26 17:40 ` [PATCH net-next 3/4] net: ipa: kill the remaining conditional validation code Alex Elder
2021-07-26 17:40 ` [PATCH net-next 4/4] net: ipa: use WARN_ON() rather than assertions Alex Elder
2021-07-26 21:52 ` [PATCH net-next 0/4] net: ipa: kill IPA_VALIDATION patchwork-bot+netdevbpf
2021-07-27 11:16 ` Leon Romanovsky
2021-07-27 12:34   ` Alex Elder
2021-07-27 12:56     ` Leon Romanovsky
2021-07-27 13:40       ` Alex Elder
2021-07-27 14:03         ` Leon Romanovsky

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