Re: [PATCH] w1: w1_therm: fix missing therm_bulk_read sysfs attribute with multiple bus masters

[Lorenzo Castellani <lorenzo.castellani@pd.infn.it>]

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The patch is attached.

Lorenzo


Il 30/09/2026 07:23, Krzysztof Kozlowski ha scritto:
> On 27/09/2026 12:43, lorenzo.castellani wrote:
>>   From 32e145b49cf41ce150a97ce52c63f5aae1bbbea7 Mon Sep 17 00:00:00 2001
>> From: Lorenzo Castellani <lorenzo.castellani@pd.infn.it>
>> Date: Tue, 22 Sep 2026 11:12:30 +0200
>> Subject: [PATCH] w1: w1_therm: fix missing therm_bulk_read sysfs attribute
>>    with multiple bus masters
> Your mailing is corrupted.
>
>> +static int w1_therm_count_bulk_read_slaves(struct w1_master *dev_master,
>> +    struct w1_slave *exclude_sl)
>> +{
>> +    struct w1_slave *sl;
>> +    int count = 0;
>> +
>> +    list_for_each_entry(sl, &dev_master->slist, w1_slave_entry) {
>> +        if (sl != exclude_sl && sl->family_data && bulk_read_support(sl))
>> +            count++;
>> +    }
>> +    return count;
>> +}
> And here.
>
> Best regards,
> Krzysztof

-- 
--------------------------------------
Lorenzo Castellani
Istituto Nazionale di Fisica Nucleare
Sezione di Padova
Via Marzolo 8
35131 PADOVA
Italy
E-mail: lorenzo.castellani@pd.infn.it
Phone:  +39 049 9677227
--------------------------------------

[-- Attachment #2: 0001-w1-w1_therm-fix-missing-therm_bulk_read-sysfs-attrib.patch --]
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From 32e145b49cf41ce150a97ce52c63f5aae1bbbea7 Mon Sep 17 00:00:00 2001
From: Lorenzo Castellani <lorenzo.castellani@pd.infn.it>
Date: Tue, 22 Sep 2026 11:12:30 +0200
Subject: [PATCH] w1: w1_therm: fix missing therm_bulk_read sysfs attribute
 with multiple bus masters

When multiple 1-Wire bus masters are present in the
system, the global module-level counter causes the
therm_bulk_read sysfs attribute to be created only
for the first master where a bulk-read capable slave
is discovered. Subsequent bus masters fail to expose
the attribute because the counter is already non-zero.

Fix this by replacing the global static counter with
a per-master helper function that iterates over the
slaves associated specifically with the given master
(dev_master->slist). This ensures that each bus
master independently correctly tracks and exposes the
therm_bulk_read sysfs attribute when bulk-read
capable devices are present.

Signed-off-by: Lorenzo Castellani <lorenzo.castellani@pd.infn.it>
---
 linux-rpi-6.18.y/drivers/w1/slaves/w1_therm.c | 30 ++++++++++++-------
 1 file changed, 20 insertions(+), 10 deletions(-)

diff --git a/linux-rpi-6.18.y/drivers/w1/slaves/w1_therm.c b/linux-rpi-6.18.y/drivers/w1/slaves/w1_therm.c
index 832e3da94..4c8e67ec8 100644
--- a/linux-rpi-6.18.y/drivers/w1/slaves/w1_therm.c
+++ b/linux-rpi-6.18.y/drivers/w1/slaves/w1_therm.c
@@ -44,9 +44,6 @@
 static int w1_strong_pullup = 1;
 module_param_named(strong_pullup, w1_strong_pullup, int, 0);
 
-/* Counter for devices supporting bulk reading */
-static u16 bulk_read_device_counter; /* =0 as per C standard */
-
 /* This command should be in public header w1.h but is not */
 #define W1_RECALL_EEPROM	0xB8
 
@@ -968,6 +965,19 @@ static inline s8 int_to_short(int i)
 
 /* Interface Functions */
 
+static int w1_therm_count_bulk_read_slaves(struct w1_master *dev_master,
+	struct w1_slave *exclude_sl)
+{
+	struct w1_slave *sl;
+	int count = 0;
+
+	list_for_each_entry(sl, &dev_master->slist, w1_slave_entry) {
+		if (sl != exclude_sl && sl->family_data && bulk_read_support(sl))
+			count++;
+	}
+	return count;
+}
+
 static int w1_therm_add_slave(struct w1_slave *sl)
 {
 	struct w1_therm_family_converter *sl_family_conv;
@@ -992,9 +1002,11 @@ static int w1_therm_add_slave(struct w1_slave *sl)
 	if (bulk_read_support(sl)) {
 		/*
 		 * add the sys entry to trigger bulk_read
-		 * at master level only the 1st time
+		 * at master level only the 1st time on this master
 		 */
-		if (!bulk_read_device_counter) {
+		int bulk_count = w1_therm_count_bulk_read_slaves(sl->master, sl);
+
+		if (!bulk_count) {
 			int err = device_create_file(&sl->master->dev,
 				&dev_attr_therm_bulk_read);
 
@@ -1003,8 +1015,6 @@ static int w1_therm_add_slave(struct w1_slave *sl)
 				"%s: Device has been added, but bulk read is unavailable. err=%d\n",
 				__func__, err);
 		}
-		/* Increment the counter */
-		bulk_read_device_counter++;
 	}
 
 	/* Getting the power mode of the device {external, parasite} */
@@ -1040,9 +1050,9 @@ static void w1_therm_remove_slave(struct w1_slave *sl)
 	int refcnt = atomic_sub_return(1, THERM_REFCNT(sl->family_data));
 
 	if (bulk_read_support(sl)) {
-		bulk_read_device_counter--;
-		/* Delete the entry if no more device support the feature */
-		if (!bulk_read_device_counter)
+		int bulk_count = w1_therm_count_bulk_read_slaves(sl->master, sl);
+		/* Delete the entry if no more device support the feature on this master */
+		if (!bulk_count)
 			device_remove_file(&sl->master->dev,
 				&dev_attr_therm_bulk_read);
 	}
-- 
2.43.0